264 MEDUSA OF THE WORLD. 



main stem is stolonic and tortuous, and the branches that spring at right angles from it give 

 rise to the polypites and reproductive calycles. These side branches or pedicels rarely give 

 rise to secondary branches. They are about 5 to 8 mm. in length, always ringed at base and 

 tip. The middle region also is sometimes ringed. The hydrothecae are bell-shaped and quite 

 large, and their rims display 10 to 14 triangular teeth. The polypites have 15 to 20 long, 

 slender tentacles; the mouth is at the end of a well-developed proboscis. The reproductive 

 calycles usually arise from the stolon, but occasionally they bud out from the sides of the pedi- 

 cels of the polypites. They are borne upon a short, ringed stem, are large and ovate, and 

 display about 7 strongly-marked, transverse rings. Each calycle gives rise to 4 or 5 medusae. 

 At the time of liberation the medusa is about 0.75 mm. in diameter. Bell higher than broad, 

 and outer surface sprinkled over with nematocyst-cells. 4 equally developed tentacles at bases 

 of the 4 radial-tubes, and 4 rudimentary, interradial tentacles. 8 lithocysts upon sides of 

 interradial tentacles, each interradial tentacle being flanked by a pair of lithocysts. At the 

 time of liberation the gonads are already apparent upon the 4 radial-tubes (plate 32, fig. 4). 

 As development proceeds the bell becomes relatively much flatter and broader and the ten- 

 tacles increase until they number 16. 



This species is very abundant upon the northern coasts of Europe and upon the New 

 England coast of North America. It is very rare at Charleston, South Carolina, and has not 

 been seen at the Tortugas, Florida. Calkins records a similar hydroid from Puget Sound, 

 Pacific coast of North America. 



The young medusa is readily distinguished from the young of Phiahdium latiguidum 

 A. Agassiz, for in the young Phiahdium there are but 2 well-developed tentacles (plate 32, 

 fig. 4), while in E. bicophora there are 4. Moreover, in the young Phiahdium the lithocysts 

 flank the radial tentacles, while in C. volubilis they are situated upon both sides of the inter- 

 radial tentacles. Also the young Phialidium shows no trace of the gonads, while in E. bico- 

 phora they are quite apparent in most individuals immediately after liberation from the 

 hydroid calycle. The mature C. volubilis is much smaller than P. languida, tentacles are 

 less numerous, and the bell is flatter. The gonads are also smaller than in P. languida. 



Clytia folleata. 

 Plate 31, figs. 9, 10; plate 33, figs. 1-3. 



Epenlhesh folletita, McCrady, 1857, Gymn. Charleston Harbor, p. 89. 



Oceania falleaia, Agassiz, A., 1865, North Amer. Acal., p. 70. 



Epenlhesis folleala, Haeckel, 1879, Syst. der Medusen, p. 184. — Brooks, 1882, Studies Johns Hopkins Univ. Biol. Lab., vol. 

 2, p. 138 (hydroid and medusa). — Mayer, 1900, Bull. Mus. Comp. Zool. at Harvard College, vol. 37, p. 52, plate 

 41, fig. 139; 1901, Sci. Bulletin Museum Brooklyn Inst. Arts and Sci., vol. I, pp. 7, 18, plate I, figs. I, 7; 1904, Mem. 

 Nat. Sci. Museum Brooklyn Inst. Arts and Sci., vol. 1, p. 15, plate 3, figs. 16, 16a. — Nutting, 1901, Bull. U. S. Fish 

 Commission, vol. 19, p. 381, fig. 101. — Hargitt, 1904, Bull. U. S. Bureau of Fisheries, vol. 24, p. 50, plate 5, fig. 3. 



( ?) Clytia Polynesia, Agassiz, A., and Mayer, 1899, Bull. Mus. Comp. Zool. at Harvard College, vol. 32, p. 167, plate 6, fig. 20. 



Bell hemispherical or slightly flatter; about 5 mm. wide, with thin walls. 16 flexible, 

 highly contractile tentacles with hollow, tapering basal bulbs; the tentacles are equally spaced 

 around the margin, 4 of them being at the ends of the 4 radial-canals, and 3 in each of the 4 

 interradial quadrants. Tentacles slightly less than length of bell-radius when expanded. 

 16 closed marginal lithocysts, each containing a single spherical concretion. These alternate 

 in position with the 16 radial-canals. Velum well-developed. 4 straight, narrow radial-canals 

 and a simple slender ring-canal. Manubrium only about half as long as depth of bell-cavity, 

 with 4 simple, slightly recurved lips. No gastric peduncle. The 4 gonads are swollen and 

 oval and developed on the outer one-fourth to one-third of the radial-canals very near the 

 ring-canal. Entoderm of stomach, gonads, and tentacle-bulbs green. 



This medusa is abundant along the coast of North America from Cape Hatteras, south- 

 ward to the West Indies. It is found off the southern coast of New England in summer and is 

 most abundant at Tortugas, Florida, in spring, and practically disappears before August. It is 

 identical in appearance with Clytia polynesia Agassiz and Mayer, of the Fiji Islands, South 

 Pacific. 



Toung medusa. — In the young medusa, 1 mm. in diameter, the 4 radial tentacles are well 

 developed, while the 4 interradial ones are less so, and the 8 others still less. 16 lithocysts, as in 

 the adult. Gonads spherical and situated at middle points of the 4 radial tubes. Bell much 

 more hemispherical than in adult. 



