BAHAMA MEDUSiE. 



21 



The species of Olindiadae are few in number but are widely scattered. 

 Nevertlieless tlie geographical range of each species is remarkably restricted. 

 It seems probable, tlierefore, that they belong to an ancient race that has 

 suffered extinction in the greater part of the world. 



Tliey exhibit relationships both to the Eucopida3 and Trachomedusae,* and 

 are distinguished by the fact that their primitive tentacles bear adhesive 

 disks upon their aboral sides near their distal extremities. These primitive 

 tentacles are retained throughout life, and project from the sides of the 

 bell above the margin. The marginal, or "velar," tentacles are phylogenetic- 

 ally recent, and arise quite late in ontogeny. 



A study of the ontogeny of Cubaia and Olindias shows that the adhesive 

 disks of their primitive tentacles are formed from modified nematocyst cells 

 which gradually group themselves so as to form a cup-shaped or pad-like 

 cluster. 



ANALYSIS OF THE GBNEEA OP OLINDIAD^. 



GENERA. 



Gonionemus . 



Cubaia 



Vallentinia . . 

 Olindias 



Olindioldes . . 



TENTACLES. 

 Of one sort only. All have 

 adhesive disks and project 

 from sides of bell. 



Two sets of tentacles, one 

 set projecting from sides 

 of bell ; other set arising 

 lower down from bell 

 margin. 



GONADS. 



CANALS. 



Ribbon-like, folded sinuously. 



4 radial canals only. 



Papilljform. 



I Sao -like . . . , 

 Papillif orm . 



6, ribbon-like. 



I 4 radial and numer- 

 ous centripetal ca- 



I nals. 



6 radial and numer- 

 ous centripetal ca- 

 nals. 



Cubaia aphrodite, Mayer. 

 Figs. JfS-^9, Plate V. 

 Mature Medusa: Figs. 45-49. Bell slightly flatter than a hemisphere and 

 about 12 mm. in diameter. About eighty tentacles. About twenty of these 

 project from the sides of the bell in a zone above the bell-margin, their en- 

 todermal axes extending through the gelatinous substance of the bell. These 

 tentacles are ringed at regular intervals with about eight nodular swellings 

 containing nematocysts. On the aboral side near the distal end of each 



* See Goto, 1903 ; Mark Anniversary Volume ; also Perkins, 1903 ; Proc. Acad. Nat. Sci. Phil- 

 adelphia, 1902, p. 750-790. 



