BAHAMA MEDUSAE. 7 
Specific Characters: The bell is thin-walled, about 0.75 mm. high and 
0.3 mm. in diameter. The bell-walls are quite rigid and the velum powerful 
and well developed. There are neither tentacles, radial canals, circular 
vessel, nor marginal sense organs. The manubrium is spindle shaped and 
about one-third as long as the bell-height. The fluids within the stomach- 
cavity are maintained in rapid motion apparently through the action of cilia. 
Near the aboral end of the bell there is a deep conical cicatrice which evi- 
dently marks the place of last connection between the medusa and its 
hydroid stock. The bell is translucent and milky in color while the manu- 
brium is cream colored. Only five specimens, all males, were found in Nassau 
Harbor, Bahamas, on the nights of July 18-19. They swam actively in arcs 
of circles, but all died early in the morning although maintained in large 
glass dishes filled with pure sea-water. They appeared to be mature, for 
sperm was discharged constantly from the sides of the manubrium. 
This is the only free swimming hydromedusa, yet described, that lacks all 
traces of tentacles, radial canals, and marginal sense organs. It is even more 
degenerate than the medusa? of Amaltha?a and Pennaria, and may be com 
pared with Eucopella ( R. von Lendenfeld, 1883 ; Zeit. ftir Wissen. Zool., Bd. 
38, p. 497), and Agastra (C. Hartlaub, Wissen. Meeresuntersuch. Biologish. 
Anstalt auf Helgoland, neu folge, Bd. 2, Heft 1, Abt. 2, p. 504, Taf. XXII, 
Fig. 5, 8-10). In these remarkable medusae we find neither manubrium nor 
marginal tentacles. There are, however, eight otocysts, and the radial and 
circular vessels are well developed. 
Syndictyon angulatum, Mayer. 
Fig. 6, Plate I. 
Mayer, 1900; Bull. Mus. Comp. Zool. at Harvard Coll., Vol. XXXVII, p. 5, Figs. 6-8. 
PI. 3. 
The bell is 3 mm. high; half egg-shaped, with moderately thick walls, 
and becomes almost square in cross section when contracted. There are four 
slender tentacles with fairly thick spindle-shaped ends. These tentacles are 
each about as long as the bell height, and their distal halves are armed with 
nematocysts. The basal bulbs of the tentacles are not very large and each 
one bears an ocellus formed by a cup-like invagination of ectodermal cells. 
The velum is large, and the radial canals and circular vessel are of fine 
calibre. The manubrium is spindle-shaped with a narrow tubular cesophagus, 
