172 MKDUS.E OF THE WOULD. 



Bougainvillia obscura Bonnevie. 



li'iugaim-illia ohscura, BDNMVIK, 1899, Bergens Mus. Aarbog for 1898, No. 5, p. 7, taf. i, fig. 4, 40. 



The hydroid is small, about 20 mm. high. The hydrocaulus of the trophosome is about 

 4 mm. high, with almost opaque perisarc without foldings or rings. The polypites are about 

 2 mm. long, nearly cylindrical and with about 15 very long tentacles. The medusae are set free, 

 and are produced either singly or in small clusters upon branched processes immediately under 

 the hydranths. 



Found at Christiania. Color ( ?) Hydrorhiza ( ?) Description of medusae ( ?) The 

 species is said to differ from other Bougainvilliae in its smooth, opaque perisarc, and in its long 

 tentacles. It will be difficult to rediscover this form from its very meager description. 



Bougainvillia glorietta Torrey. 

 Bougainvillia ghriftta, TORREY, 1904, Univ. California Publications, Zool., vol. 2, No. i, p. 7, figs. 2, 3. 



Stems branched, rising trom a creeping hydrorhiza in clusters to the height of 20 to 30 mm. 

 The stems and branches often twine about each other. Perisarc smooth, or wavy, covered with 

 particles of detritus. Terminal polypites largest, with 20 to 25 tentacles in 2 or 3 irregular 

 whorls, the outermost being the shortest. Tentacles highly contractile. Gonophores in groups 

 of 2 or 3 on branches or hydranth stalks, mounted on short pedicels. The well-developed 

 medusae within the gonophores have 4 pairs of marginal, 4 simple, oral tentacles, and 8 ocelli. 

 Color ( ?) Found at San Diego, California. 



Distinguished by its smooth, unannulated perisarc and twining stems. Free medusa is 

 unknown. 



Genus NEMOPSIS L. Agassiz, 1849. 



A>wo/m.<, AGASSIZ, L., 1X49, Mem. Anier. Acad., New Series, vol. 4, p. 289; 1862, Cont. Nat. Hist. U. S., vol. 4, p. 34^. 

 McC-RADY, 1857, Gyrnn. Charleston Harbor, p. 58. AGASSIZ, A., 1862, Proc. Boston Soc. Nat. Hist., vol. 9, p. 98; 1865, 

 North Amer. Acal., p. 149. HAF.CKEL, i879,Syst.der Medusen, p. 92. BROOKS, 1883, Studies Biol. Lab. Johns Hopkins 

 University, vol. 2, p. 468. HARGITT, 1904, Bull. U. S. Bureau of Fisheries, vol. 24, p. 37. 



This genus was founded by L. Agassiz, 1849, t r Nemopsis bachci of the Atlantic coast of 

 the United States south of Cape Cod. 



GENERIC CHARACTERS. 



Margelmae with 4 clusters of marginal tentacles, one at the extremity of each of the radial- 

 canals. There are two sorts of tentacles in each cluster, a median pair of club-shaped tentacles 

 with swollen extremities studded with nematocysts; and on both sides of this median pair 

 there are a number of simple, filiform tentacles. The 4 radial lobes of the stomach extend out- 

 ward along the radial-canals and the gonads are developed along the sides of these lobes. The 

 hydroid is a Bougainvillia. In the Nemopsis hydroid, however, the medusae arise from the 

 sides of the naked polypites, not trom the branches of the stems of the hydroid, as is usual in 

 other species of Bougainvillia. 



In common with Bougainvillia the medusa of Nemopsis has 4 dichotomously branching, 

 oral tentacles. Its most striking feature is the wide extension of the 4 radial pouches of the 

 stomach along the 4 radial-canals. This is, however, not of generic value, for it occurs to a 

 greater or less degree in Bougainvillia. The sole distinctive generic feature of N emopsis is the 

 presence of two distinct sorts of tentacles upon each marginal bulb. L. Agassiz, in his first 

 brief notice of this genus in 1849, called attention to its peculiar club-like median pair of ten- 

 tacles and presents a good figure of them, but his description is not wholly correct, for the ocelli 

 are not upon the ends of the tentacles, but are on the axial (inner) side of each tentacle adjacent 

 to the pad-like base. 



Haeckel, 1879, considers Nemopsis to be identical with Favonia of Peron and Lesueur, 

 1809; nevertheless he adopts the name Nemopsis, although maintaining the precedence of 

 Fnvnnin. I agree with VanhSfFen, 1891, and consider that Favonia is certainly not equivalent 

 to Nemopsis. Blainville's (1834, Man. d'Actinologie) copy of Peron and Lesueur's figure of 



