J 
: 
i i a A i ee ee 
—_—e a re 
nascent 
AGASSIZ AND MAYER: ACALEPHS FROM THE FIJI ISLANDS. 179 
This species is very closely related to Spheronectes gracilis, Claus, of the 
Mediterranean and Tropical Atlantic.1 We have taken S. gracilis at the Dry 
Tortugas Islands, Florida. 
Diphyopsis angustata, Harcket. 
Plate 17, Fig. 54. 
Diphyes angustata, Eschscholtz, F., 1829, Syst. der Acalephs, p. 136, Taf. 12, 
Fig. 6. 
Diphyopsis angustata, Haeckel, E., 1888, Challenger Report, Zodl., Vol. XXVIII. 
pp. 152, 363. 
Generic Characters. Diphyopsis, Haeckel, 1888. Diphyide with two angu- 
lar, slenderly pyramidal swimming bells of similar form and subequal size, 
one placed behind the other. The first swimming bell possesses a complete 
infundibular hydreecium on its ventral side. The groups of units upon the 
hydrosoma are Eudoxiform, and are separated by free internodes. Each feed- 
ing polyp possesses a covering scale. The covering scales are spathiform, with 
a deep ventral groove. 
Specific Characters. The specimens found by us conform to the definition of 
the genus Diphyopsis, with the notable exception that we observed no posterior 
swimming bell, such as is figured by Haeckel (1888, Plate XXXIII.) in Di- 
phyopsis compressa. It is possible that no such structure exists in Diphyopsis 
angustata, but knowing the ease with which swimming bells are broken off and 
lost, we hesitate to make such astatement. The anterior swimming bell (the only 
one observed) is 37 mm. in length. The bell cavity is long and spindle-shaped, 
and terminates in a long, narrow neck, in the end of which there are usually a 
number of vacuolated cells containing green pigment (cp., Fig. 54). There is 
a well developed velum, the sudden contractions of which cause the animal to 
shoot rapidly through the water. There is a circular vessel within the swim- 
ming bell, and also two long curving side tubes (7, r, Fig. 54). These com- 
municate by means of a long duct (c) with the gastro-vascular cavity of the 
hydrosoma. The cavity of the hydrecium is about 17 mm. in depth. There 
is a long spindle-shaped mass of vacuolated cells (f) extending from the inner 
apex of the hydrwcium into the gelatinous substance of the swimming bell. 
The hydrosoma also arises from the inner apex of the hydrecium. It often 
attains a length of 100 mm., and there are numerous groups of units (cor- 
midia) found upon it. These are separated one from another by free inter- 
nodes. The cormidia all arise from the ventral side of the hydrosoma. The 
first to appear are the feeding polyps. Then follow, in order, the tentacles and 
the covering scales. No gonads or swimming bells were seen. Each covering 
scale possesses a deep open groove along its ventral side. The tentacles give 
off simple lateral filaments that terminate in nematocystic bulbs. The ento- 
1 See Chun, C., 1892, Abhandl. d. Senckenb. naturf. Ges., Bd. XVIII. p. 84, 
Fig. 5. 
