failed to notice the small fragments of stone which often darken and sometimes cover the surface. When these are examined they are found to be sharply angular; and if the examination is extended to the medial and lateral moraines, they will be found to contain immense quantities of similar materials. These small fragments, as well as large ones, find their way into the sub-glacial streams, in which by the sharpness of their angles they become most effective instruments in the work of erosion. The materials transported by ordinary streams, even when swollen by heavy rains, are of a different nature. The small stones and gravels which they receive are usually more or less rounded, while the finer materials are chiefly loam, clay, soil, or well-worn sand. The erosive power of a current carrying such old, worn, and often soft materials, is much less than that of one charged with the new and sharp instruments of the sub-glacial streams; hence the denuding agency of the latter should not be estimated by observations upon the former.

The excavating power of these streams is shown in the number of pot holes which they produce. The steepness and irreg ularity of their courses, the abundance of water with stones and sand, and in many places the presence of ice causing gyratory movements of the water, make these streams peculiarly efficient in this work. Sometimes these pot-holes succeed each other so closely in the course of the stream, that as they increase in size they unite and form a deep, narrow gorge, whose walls present a succession of their concave surfaces.

Furthermore, the ice of the glaciers often exercises a controlling influence upon the positions and courses of these streams. It is not uncommon to find a stream flowing along the edge of the glacier considerably below its surface, in a channel one side of which is ice and the other side rock. In such instances the streams are often supported by the ice at a considerable elevation above the bottom of the valley where they would otherwise be. The power which a glacier may have for preventing water from flowing directly into the lower portion of its valley, is well illustrated by the Märjelen See, a lake which owes its existence to the ice-wall of the side of the Great Aletsch Glacier which forms one end of the basin which it occupies.

The lateral streams above described are abundantly supplied with small and large pieces of stone from the lateral moraines, and they thus become agents in the erosion of the sides of the valleys. It will probably be remarked that such streams must naturally erode the ice more rapidly than the rock, but it must be remembered that the ice is constantly renewed by the motion of the glacier. It will be readily seen that such streams, by the peculiarities of their situation and action must exercise an influence in determining the precipitous character which the sides

of glacial valleys so often have. If it is objected that such water-worn surfaces are rarely met with upon the sides of valleys from which the glaciers have retreated, it must be remembered that the ice above the streams and the atmospheric agencies modify these surfaces after they have been left by the streams, hence the rocks have the features which they received from the last agent which acted upon them.

Still lower and quite underneath the side of the glacier there are larger and often much longer lateral streams, which are much more important agents in the excavation and formation of the valleys. These, flowing in channels of their own formation in the rock and quite below the ice, tend to deepen the valley along its edges and to give it that cañon-like form so often seen.

Sometimes the aqueous erosion under the sides of a glacier is greater than it is under the medial portion, and when this has been continued for long periods the edges of the valley have become the deepest portions, and when the lower end of the glacier has receded to this part of the valley it is often bifurcated, its terminations being upon opposite sides of the rocky eminence left in the central part of the valley. Such knolls or hills occur in the valleys of ancient glaciers, as, for example, in the valley of the Rhone at Sion, and they have always been a puzzle to the advocates of a purely glacial origin of such valleys. If, however, we duly recognize the power of sub-glacial streams, the hills which are sometimes left in positions where they have been fully exposed to the action of glaciers appear as a normal and not as an anomalous result of the agencies which have excavated such valleys.

With many other glaciers and often with other parts of the same glacier, the medial stream is the most important one in volume and power, and then it tends to make that part of the valley the deepest, and the glacier assumes a corresponding form.

In conclusion I will state that the observations of three summers among the glaciers of the Alps have led me to estimate the relative agency of glaciers and sub-glacial streams in the erosion of valleys as follows: viz., that the sub-glacial streams are of primary importance in working in advance of the ice in deepening and enlarging these valleys, and that the glaciers abrade, modify, and in a measure reduce the prominent portions left by the streams, and give them the well-known glaciated surfaces.

[I have not space in the narrow limits of this article to consider the valuable and exceedingly numerous contributions of others to the subject of glacial action.]

ART. XLVI.-Notice of recent additions to the Marine Fauna of the eastern coast of North America, No. 2; by A. E. VERRILL. Brief contributions to Zoology from the Museum of Yale College. No. XXXIX.

DURING the past summer Professor Baird established the headquarters of the U. S. Fish Commission at Gloucester, Mass. Numerous dredgings were made under the direction of the writer, in the U. S. Steamer Speedwell, commander Beardslee. Mr. Richard Rathbun, Mr. Sanderson Smith and others assisted in the invertebrate department, while Mr. G. Brown Goode, Mr. T. H. Bean and Mr. R. E. Earll, took charge of the Ichthyology. The temperatures were taken by Mr. Asaph Hall, Jr. Our dredgings extended over Massachusetts Bay and Stellwagen's Bank, and to the deeper waters of the Gulf of Maine, about forty-five miles east of Cape Ann. Although a very large and valuable collection, containing many additions to the fauna, was obtained by means of our dredges and trawls, more novelties, both among the fishes and invertebrates, were secured by inducing the fishermen engaged, in the fisheries of halibut and cod on the outer banks, to preserve and bring in the various things that become entangled in their trawllines. Many of the following species, some of them of great interest, were thus obtained by the fishermen, together with numerous specimens of many better known species, among which the most conspicuous and abundant are large and fine specimens of the corals, Paragorgia arborea and Primnoa reseda, while Acanella Normani has recently been brought in from many localities in considerable numbers.

ECHINODERMATA.

Pteraster pulvillus Sars. Norges Ecinod., p. 62, Pl. 6, figs. 14–16, Pl. 7, 8.

A well-developed specimen of this species was dredged in thirty-five fathoms, off the Isles of Shoals, N. H., by Dr. A. S. Packard, on the "Bache," in 1874. It may be distinguished from P. militaris by its more warty surface, more swollen form, with the rays narrower below and the transverse spines fewer, less prominent and less acute.

Porania grandis, sp. nov.

The greater radius of the larger one is 4.75 inches; radius of disk, 2-75. The greater radius of another is 4:35 inches; of disk, 2-70. The upper side, when fresh, was bright cherry-red; lower surface pale yellow. Easily distinguished by the nearly smooth, fleshy surface, without spines; but with two regular broad bands of soft slender papillæ along each ray on the upper side, and with radiating grooves on the lower side, which extend

also to the upper surface. Margin of disk without distinct spines, but with irregular rudimentary tubercles, covered by the skin. Adambulacral spines forming an inner row, two, united by a basal web, on each plate, and an outer series arranged in oblique transverse groups of about three; these are shorter and covered by the skin, which is everywhere finely granulose. No interbrachial spines, except one or two rudimentary ones, close to the mouth.

Two large and fine specimens of this species were taken on trawl-lines on the eastern slope of George's Bank, in about 220 fathoms, and presented by Capt. Anderson and the crew of the schooner Alice G. Wonson, August, 1878.

Asterina pygmæa, sp. nov.

A small species, perhaps young, with a rather flattened pentagonal disk, with edges concave, and very short obtuse rays. Upper surface covered with small, sub-acute, stoutish spines on the disk, mostly placed singly and not crowded; on the rays mostly in transverse groups of two or three on each plate. A short row of few conspicuous solitary pores for the papulæ are on each side of the base of the rays; margin of disk thin, fringed by a row of small slender spines borne on the ventral row of plates, which project more than the smaller dorsal ones; the latter bear a group of very small inconspicuous spines, and belong to the upper surface. Beneath, the disk is covered with soft skin, showing conspicuous radiating furrows between the relatively large, oblong, marginal plates, each of which bears a row of four to six small, slender, marginal spines on its outer end, but is elsewhere smooth, or, when dry, minutely granulose. There are eight of these plates on each interradial margin. The triangular interradial area has a few plates, some of which have one small acute spine. The ambulacral grooves are bordered by two rows of small, acute, rather stout spines on each side, those of the outer row usually standing erect, those of the inner ones often interlacing across the groove. Usually one inner and one outer spine to each plate, but close to the mouth, two inner ones sometimes on one plate. Smaller radius, 3.5mm; greater, 5mm.

Cashe's Ledge, Gulf of Maine, fifty-two to ninety fathoms. Dredged by Dr. Packard and Mr. Cooke on the "Bache," in 1873. Archaster Flora, sp. nov.

Five rays; greater radii, 85 to 88mm: smaller, 15 to 18mm; breadth of arms at base, about 20mm; in middle, about 12mm; paxilligerous portion in middle, 7 to 9mm, or about twice as wide as upper marginal plates. Disk moderately large, flat, with the central opening raised on a slight eminence. Arms elongated, flat above, regularly tapered to slender acute tips. Dorsal surface with the paxillæ evenly and regularly arranged, mostly with

about fourteen to eighteen small, short, round-tipped spinules at the summit; of these, ten to twelve are usually divergent and border the edge, and are a little longer and more slender than the four to six more rounded ones that form a central group. Marginal plates forty-five to forty-eight on each side; upper ones mostly higher than long, except toward the tips, even and regular, thickly covered with small spinules which are finer and more slender around the margins, where they are crowded and divergent, those over the central part being shorter, larger and more obtuse, with occasionally one or two, small, acute spines rising from the center of the plate, especially along the middle of the arm. Lower marginal plates opposite the upper and a little higher, covered with the same kinds of spinules, but mostly having a central, vertical row of two to four, slender, acute, spines, which are more or less appressed and scarcely longer than the plates, but longer than those on the upper plates. Adambulacral plates each with an inner fan-shaped group of eight or nine, slender, rather long spines, the central, longest, and with an outer, more or less circular, loose, divergent cluster of eight to ten shorter, slender spines; a similar, but mostly smaller and more regular, cluster occupies each of the pavement-like plates that cover the triangular interbrachial area and extend out along the arms between the marginal and adambulacral plates, in about three rows toward the base, but gradually narrowing to one, farther out.

Oral plates prominent, forming narrow elliptical "jaws" surrounded by two close rows of short spines, those of the inner row slightly divergent with enlarged rough tips, in close contact; those of the outer row shorter, with the tips flattened and closely pressed against the inner ones, so as to support them externally.

Color, in life, light purplish red above, yellow beneath. Dredged by us in 1877, about thirty miles south from Halifax, N. S., in 100 fathoms, fine compact sandy mud, associated with Archaster arcticus, Astrogonium granulare, Asterias stellionura, Hippasteria phrygiana, Antedon Eschrichtzii, Pennatula aculeata, Eudendrium rameum, etc.

Ophiacantha sp. Related to 0. cosmica (fide Lyman).

Distinguished by having the disk thickly covered with minute, three-pronged, slender spinules. Mouth-plates extending into interbrachial spaces. Eastern slope of George's Bank, 220 fathoms, (schooner " Alice G. Wonson.")

Astrophyton eucnemis Müll. and Troschel.

Several specimens of this species, not before known south of the Gulf of St. Lawrence, were found clinging to specimens of Paragorgia arborea, from the eastern slope of George's Bank, in about 220 fathoms, (schooner " Alice G. Wonson.")