62 BULLETIN: MUSEUM OF COMPAKATIYE ZOOLOGY. 



was found at the Tortugas, Florida, iu June, 1897. This remarkable species 

 is extremely inactive. Owing to the small size of the velum, it is of but little 

 service in swimming, and the medusa makes use of the contractions of its 

 widely open mouth in order to propel itself through the water. 



GONIONEMUS, Agassiz, a., 1865. 



Gonionemus aphrodite. 



Cubaia aphrodite, Mayer, A. G., 1894, Bull. Mus. Comp. Zool. at Harvard Coll., 

 VoL XXV. p. 237, PI. n. Figs. 1-3. 



This medusa is occasionally met with at the Tortugas, Florida, and an 

 examination of mature individuals has convinced me that it belongs to the 

 genus Gonionemus. The gonads consist of a series of finger-shaped, or papilli- 

 form, processes that are crowded alternately to one side and the other of the 

 radial canal very much as in the species of Gonionemus found at Woods HoU, 

 Massachusetts. 



GONIONEMOIDES, nov. gen. 

 Gonionemoides geophila, nov. sp. 



Figs. 6-11, Plates 3-5. 



Generic Characters. — This genus is closely related to Gonionemus, but differs 

 from it in that the marginal tentacles are of two distinct kinds, and arise at 

 slightly different levels from the bell margin. One of these sets of tentacles is 

 provided with nettling cells, and the other is furnished with adhesive suckers, 

 as in Gonionemus. There are 4 radial canals, and the circular vessel is simple 

 without centripetal canals. The gonads are papilliform and are situated upon 

 the radial canals. There ate numerous otocysts upon the bell margin. 



Specific Characters. — Adult medusa, Figures 6-9. The bell is quite flat 

 and disk-shaped, and is about 9.5 mm. in diameter. There are 64 marginal 

 tentacles. 16 of these bear, each one, a suctorial disk upon the aboral sides 

 near their distal extremities. The extreme distal ends of the tentacles are 

 cone-shaped, and are bent sharply at a right angle to the main shaft of the 

 tentacle, very much as is the case in Gonionemus vertens, A. Agassiz. These 

 sucker-bearing tentacles arise at a level, a little above the bell margin. The 

 remaining 48 tentacles all arise from the bell margin, at a lower level than do 

 the sucker-bearing ones. They possess no suctorial disks, but instead are 

 armed with rings of nematocyst capsules (Figure 6). These nematocyst- bear- 

 ing tentacles are far more flexible than are the sucker-bearing ones. 



There are 12 otocysts upon the bell margin, each one of which contains a 

 single otolith situated within an elongate, oval cavity (.see Figure 7). The 



