Nausithoë punctata Kölliker, pp. 554–556, pl. 60, figs. 4–5, text fig. 352.1

This medusae is noteworthy for the peculiar, branched scyphistoma which lives commensally in sponges. Found in all tropical and warm seas.

Linuche unguiculata Eschscholtz, pp. 558-559, pl. 59, figs. 1-10.

A West Indian species. Forms vast swarms in spring in the Florida-Bahama region according to Mayer. Dactylometra quinquecirrha L. Agassiz, pp. 585-588, pls. 62-64a, text figs. 370–372.

Widely distributed from New England to the tropics; possibly also Pacific. Abundant in Tampa Bay in August (p. 586).

Cyanaea capillata var. versicolor L. Agassiz, pp. 600-601, pl. 65, figs. 1-2.

Western Atlantic and Gulf, south of Cape Hatteras.

Aurellia aurita Lamarck, pp. 623-626, pl. 67, figs. 1-4, fig. 4; 68.

In east American waters, common from Greenland to West Indies.

World wide.

1 See footnote 2, page 277.

Cassiopea xamachana R. P. Bigelow, pp. 641-646, pls. 69-72. C. frondosa Lamarck. Pp. 647-648, pl. 69 and 72.

These interesting medusae are the subject of several papers in the Tortugas Laboratory series. The first is known from Tortugas and Jamaica; the second is more widely distributed throughout the West Indies. Rhopilema verrillii (Fewkes), pp. 707-709, pl. 7, fig. 1, text fig. 424.

From New Haven to Port Aransas, but not (?) Tortugas.

Stomolophus meleagris L. Agassiz, pp. 710-711, pls. 75-76. Abundant along southern Atlantic and Gulf of Mexico (not north of Chesapeake Bay), and West Indies. Also on Pacific side of Isthmus, and north at least to San Diego.

LITERATURE CITED

HEDGPETH, JOEL W.

1945. Reexamination of the adventure of the Lion's Mane. Sci. Monthly 60: 227-232.

MAYER, A. G.

1910. Medusae of the world. Carnegie Inst. Washington Pub. 109, 3: 499-735.

This table has been compiled from the literature and from collections in the U. S. National Museum, including unpublished records from the Albatross, Fish Hawk, and Pelican expeditions. Published locality records within the Gulf of Mexico as defined above have been located for 72 species; records of only 9 species from Gulf localities exclusive of the lower Florida Keys and Tortugas have been found. Another 19 species have been added by records in the collections of the U. S. National Museum, bringing the total number of species to 91. These species represent 18 families in 4 of the 6 known orders.

Although little is known of the physiology of the alcyonarians, it is clear that bottom conditions, temperature, salinity, available oxygen, and sedimentation play important parts in limiting their distribution. Limits of tolerance are apparently quite narrow but not equally so for all factors. A solid substrate providing satisfactory conditions for the attachment of larvae is almost universally required among all alcyonarian groups excepting the pennatulids. A very few gorgonacean species are able to live unattached, and a number, especially of the families Chrysogorgiidae and Isididae, can adapt themselves to live

on either hard or soft bottom. The few gorgonian species which have been investigated in regard to temperature tolerance (L. R. Cary, Papers from the Dept. of Marine Biology, Carnegie Institution of Washington, v. 12, No. 9, 1918) can withstand from 5° to 9° C. (approximately) above the average maximum surface temperature of the area (at the Tortugas, about 29° C.), but it is unlikely that colonies would establish or thrive outside of a rather limited temperature range. In the absence of experimental evidence, it is impossible to state the limits of the salinity and oxygen variation which the alcyonarians can tolerate. A few species can live in situations where the salinity is occasionally somewhat reduced, but most, including the West Indian reef-dwelling forms, are never found where appreciable dilution regularly occurs. Certain species are limited to outer reef situations, and oxygen may be the critical factor in such cases. As a rule, alcyonarians are not found in continuously muddy waters, but some can tolerate very muddy conditions for short periods.

The reef areas of the Tortugas and lower Florida Keys support a typically West Indian gorgonian assemblage. The predominant families are the

N

Plexauridae and the Gorgoniidae; while not all of the known West Indian members of these families have been recorded from this area, most are to be expected. This community does not extend northward undiminished for any appreciable distance, although a few of the hardier species range about halfway up the Florida west coast. The scarcity of suitable reef-like situations along this coast seems to account in part for their reduction in numbers, and temperature may be of equal importance in limiting the northward distribution of shallow-water gorgonians. Antillogorgia acerosa, A. americana, and Pterogorgia anceps are characteristic reef forms which extend some distance up the west coast of Florida, and they probably occur wherever there is solid bottom suitable for attachment and permanent support. The predominant West Indian genera of reefdwelling gorgonians, Plexaurella, Eunicea, Antillogorgia, Gorgonia, Pterogorgia, and Phyllogorgia, are restricted to the warm western Atlantic, while a few, such as Pacifigorgia and Muricea, are most numerous on the Pacific coast of the middle Americas, and at least one, Leptogorgia, is found also in the eastern Atlantic, the Mediterranean, east Africa, and the East Indies.

The alcyonarian fauna of the lower west coast of Florida is thus a decimated West Indian assemblage. To the northward it merges with and soon, perhaps near Tampa, is replaced by a distinctly temperate fauna the predominant gorgonians of which are Leptogorgia virgulata and L. setacea (both of which are referable (Bayer 1952) to Verrill's genus Eugorgia), and Muricea pendula. These species are especially abundant along the coast of the Carolinas and south perhaps to northern Florida; L. virgulata extends north to New York in moderately deep water, but all three seem to be lacking from the lower east coast of Florida. The short-stemmed sea pansy, Renilla mülleri, is common in the northern Gulf and extends southward to Brazil; it likewise occurs along the Pacific Coast from Central America to Chile. It has not been recorded from the Atlantic coast of North America where the only species appears to be Renilla reniformis, the common long-stemmed sea pansy. The latter species occurs also in the Gulf of Mexico with a variety extending south to the Straits of Magellan and another in California.

The shallow-water gorgonian fauna of the northern Gulf of Mexico is clearly identical with but discontinuous from that of the Carolina coast. This interrupted distribution pattern has been pointed out by Deevey (Ecology, vol. 31, No. 3, pp. 334-367, 1950) for some hydroids and other invertebrates and is described for fishes in this volume (Rivas, p. 503). Deevey suggests that reduced temperature during periods of glaciation permitted continuity of the cool-water fauna around south Florida, but it would seem fully as plausible that this continuity existed when Florida was submerged and that subsequent dispersal around the peninsula has been prevented by a thermal barrier. Since apparently favorable situations exist all along the east coast of Florida, the southward dispersal of these discontinuously distributed gorgonians is probably not limited by bottom conditions but by some other environmental factor of which temperature seems to be the most likely. In any event, it can hardly be doubted that the present-day distribution reflects a former continuity of the Gulf and Carolina faunas, but a satisfactory explanation must await the study of some group with an extensive fossil record.

Although its southern limit is not known, the shallow water temperate assemblage is probably present along most of the Texas coast, somewhere along the coast of Mexico mingling with and giving way to the hardier elements of the West Indian fauna which encroach upon it from the south. At least one gorgonacean, Leptogorgia setacea, extends as far south as the Guianas and Trinidad.

The presence of actively growing coral reefs at Veracruz and along the coast of Yucatán has long been recognized, but the composition of their fauna is little known. Heilprin (1890) reports only one species of gorgonian from the Veracruz reefs and remarks that the vast gorgonian sea gardens so typical of the Bermudas are lacking. The single species that he records, Plexaura flexuosa, belongs to the West Indian fauna, and it seems likely that other West Indian species occur there. Heilprin notes further that Xiphigorgia (now Pterogorgia) anceps was found at Progreso, Yucatán, another record indicative of the West Indian fauna. The occurrence of the West Indian reef species Gorgonia flabellum on