este," Professor Claus has edited the first part of a handsome volume containing memoirs on the minute structure of the Siphonophores, represented by the Portuguese man-of-war. A paper on the male reproductive organs of the crabs, and one on the origin of the vagus nerve in the sharks, with especial reference to the electrical batteries of the torpedo, also appear in the part issued.

Most excellent work was done in this country by Professor W. K. Brooks and others, of the Johns-Hopkins University, in a zoological laboratory established during the last summer at Old Point Comfort, Va. Unfortunately, the work done (regarding the development of Lingula and Amphioxus) remains unpublished for want of means on the part of the university, as few, if any, would be found to purchase the pamphlet or work containing the memoirs, owing to the great lack of advanced students in this country like those of Germany, who purchase such works at the expense of other luxuries.

The Zoological Station of the Zoological Society of the Netherlands has published its third report. The Station during the summer of 1878 was erected on the island of Terschelling, and in the course of two months it was visited by ten zoologists for the purpose of studying the animals of the Zuyder-Zee.

The Zoological Garden in Philadelphia has been specially favored. Its management has been in the hands of gentlemen of the highest character and position, and the exceptionally large receipts coming to it during the Centennial and preceding years have so assisted its rapid development that what is usually the growth of many years has been accomplished by the Philadelphia society in a few months. This garden was opened in July, 1874. Up to March 1, 1878, it had been visited by the large number of 1,508,501 persons, and its gate receipts amounted to $226,301.79. Its collection of animals is the finest in the country, and consists of 434 mammals, 453 birds, 58 batrachians, and 63 reptiles. The beauty of the grounds, the taste with which they have been laid out, the elegance of the buildings (perhaps too costly for their purposes), and the excellence of their collection combine to make the Philadelphia Gardens compare favorably with many of the long-established gardens of the

Old World. Already some of the dissections and observations of its inhabitants have made important contributions to science. The first complete dissection and structural description of the manatee (Manatus americanus) was made from its specimens, and some valuable contributions to comparative anatomy and physiology have resulted from their observation.

Geographical Distribution of Animals.

It is now known that numerous marine animals occur in inland lakes and rivers. Several species of Blennius are found in the fresh waters of Southern Europe, says Professor Duncan, in a résumé of this subject. Gobius is a freshwater East Indian fish. Palamon jamaicensis is a fresh-water shrimp; another small shrimp, allied to certain marine ones, occurs in the fresh waters of Italy, and another shrimp lives in the Mississippi as far north as Cairo, Ill. The blind fish of the Mammoth Cave are probably descendants of marine forms. The Monolistra of the Adelsberg caves is a fresh-water representative of a Sphæroma which lives in the Pontine Marshes. Again, several families which are marine in the Mediterranean Sea, such as the scomberoids, skates, and rays, are represented in the tropics by fresh-water forms. Monocinus polyacanthus (Haeckel) inhabits the Rio Negro. Carcharias gangeticus is found sixty leagues from the sea; Pristis perroteti lives in the Senegal. Raia fluviatilis has been taken near Rampur, nearly 1000 miles above tide reach; and Schomburgk found a Trygon in the river Magdalena. The land-crab of the West Indies is represented in fresh water by a Telphusa, though all the other crabs (Brachyura) are marine. Certain mollusks, usually marine in their habits, are known to live in streams or lakes. Among Polyzoa, Hislopia lives in fresh water, and the hydroid Cordylophora is a fresh-water form. In the lakes of Sweden, Switzerland, and North America are marine species which have survived the gradual change from salt to fresh water, while it may be regarded as a general rule that all terrestrial and fresh-water life has originated from marine forms, though this rule may have had its exceptions.

Among recent papers on the mammals in the Proceedings of the Zoological Society is an essay on the Molossus bats,

by G. E. Dobson; descriptions of new mammals collected by Professor Steere in the Philippine Islands; and descriptions of some new mammals from tropical America, by Dr. Günther, who also adverts to the presence of the genus Atherura (A. africana) on the west coast of Africa. He has before drawn attention to the occurrence on the coast of West Africa of fresh-water fishes previously considered to be exclusively typical of the Indian region. Thus the reappearance of the Atherura on the West African coast strongly confirms Mr. Wallace's view that there is present among the mammals and birds of West Africa a special Oriental or even Malayan element. "Instances of this kind," adds Dr. Günther, "appear to me to be of infinitely greater weight in solving the problem of the mode of dispersion of animals. over the globe (or their genesis) than deductions drawn from lists of genera vaguely or artificially defined." He has also discovered African reptilian types in the Indian region. Dr. Coues's Field Notes on Birds observed in Dakota and Montana along the Forty-ninth Parallel during the Seasons of 1873 and 1874 appear in Hayden's Bulletin of the United States Geological Survey. Dr. Coues found that the bird fauna of the Red River region is decidedly Eastern in character; but on crossing the Coteau into the Missouri region, or the great water-shed of the Upper Missouri and Milk rivers, the whole aspect of the country changes, and the assemblage of birds is different, and few, if any, distinctively Eastern birds extend across or even into this region. This extends to the very base of the Rocky Mountains, rising gradually to them. The Rocky Mountain region is strongly marked not only by "Western" species, but by Alpine forms, by exclusively arboreal species, and by the abrupt disappearance of the prairie birds.

The Hypothesis of Evolution.

In an interesting address on the Development of the Forms of Animal Life, delivered by Professor Allen Thomson, President of the Plymouth Meeting of the British Association for the Advancement of Science, he takes the most advanced ground held by embryologists, and endorses the conclusion that the phenomena of development in animals show that all pass through in their simple forms similar

stages of development; "that in the lower grades of animal and vegetable life they are so similar as to pass by insensible gradations into each other; and that in the higher forms, while they diverge most widely in some of their aspects in the bodies belonging to the two great kingdoms of organic nature, and in the larger groups distinguishable within each of them, yet it is still possible, from the fundamental similarity of the phenomena, to trace in the transitional forms of all their varieties one great general plan of organization." He adds that, "if we admit the progressive nature of the changes of development, their similarity in different groups, and their common characters in all animals-nay, even in some respects in both plants and animals-we can scarcely refuse to recognize the possibility of continuous derivation in the history of their origin; and however far we may be, by reason of the imperfection of our knowledge of paleontology, comparative anatomy, and embryology, from realizing the precise nature of the chain of connection by which the actual descent has taken place, still there can be little doubt remaining in the mind of any unprejudiced student of embryology that it is only by the employment of such a hypothesis as that of evolution that further investigation in these several departments will be promoted so as to bring us to a fuller comprehension of the most general law which regulates the adaptation of structure to function in the universe."

In a richly illustrated volume on the embryology and anatomy of the starfish, Mr. Alexander Agassiz takes exception to the prevailing Darwinian views in the following language: "While," he says, "the successive appearance of the great types of Echini in geological time-in other words, their paleontological development-is in the strictest harmony with what we know of their embryological development, we as certainly know nothing whatever of the causes which have brought about their sequence in time, in such striking agreement with the sequence in their phases of growth. The case of successive modifications of the ancestral horse, which has so often been brought forward as conclusive regarding the genealogy of the group, although more familiar, is far less complete and much more limited in time than the succession to be traced from the paleontological evidence of Echini. But, while natural selection gives a plausible explanation of

like problems among Vertebrates, it fails utterly when applied to the majority of the Invertebrates, and we have completely failed, thus far, to find any causes for their paleontological development differing from those acting upon their successive embryological stages at the present day, of which we know absolutely nothing.'

In a paper on the Birds of Guadalupe Island, off the coast of Southern California, Mr. R. Ridgway discusses the subject with reference to the genesis of species. There are only eight species, and their affinities are almost entirely, as would be expected, with those of Western North America. Yet they are so far differentiated from them that they are recognized by Mr. Ridgway as specifically distinct. They all differ somewhat similarly from their nearest mainland allies in their principal features—namely, in (1) “increased size of the bill and feet, (2) shorter wings and tail, and (3) darker colors." These facts, adds the reviewer, point emphatically to the directly modifying influence of the peculiar conditions of environment to which they are subjected; and, taken with other now well-known facts, lead to the conclusion that the present differentiation of species and subspecies is mainly the result of the immediate action of climatic and other surrounding conditions.

Some remarkable observations of Schmankewitsch on the influence of external surroundings on the organization of animals have recently been published in Siebold and Kölliker's Zeitschrift. This refers to changes in Artemia and Branchipus, two allied genera of Crustacea. In a former article, published in 1875 in the Russian language, he discussed the differences between the fresh- and salt-water forms of Cyclops and allied forms, Daphnia and Artemia and Branchipus, and showed that several species are produced by difference in the density of the water and absence or presence of salt, with results of unusual interest and pertinence to discussions on the origin of species and genera.

From his studies of the nautilus and its fossil allies, Barrande infers that the type has undergone no modifications from the Silurian period to the present day, and that the facts elicited do not favor the evolution theory.