250 



CCELENTERATA. 



To these is usually added a funnel or umbrella-shaped hydrophyl- 

 liuni (fig. 192). These groups of individuals may in some Diphyids 

 become free, and assume a separate existence as Eudoxia (fig. 193). 

 The gonophores contain numerous ova in the nianubrium, which 

 often projects as a cone from the aperture of the bell. In the larva 

 the upper nectocalyx is the first formed. 



F.im. Hippopodidae. The swimming column has two rows of nectocalyces, 

 and is situate on an upper lateral branch of the stem. The male and female 

 gonophores are grouped in clusters and are situate at the base of the nutritive 

 polyp. Crli'lm H\i>p<i}>ux Forsk., Mediterranean. 



Fam. Diphyidae. With two very large nectocalyces at the upper end of the 

 stem and opposite to each other. Diplnjfx iicuminatti Lkt., dioecious ; with 



Eiido,r}u cKmjianiilatii. Aliyln pmtuijona Esch., with 

 EiuJo.rid mlio'idex, Mediterranean. Spliceroneetes 

 Huxl. = J/^r//;////r.v ('Is., ty. i/n/cili* Cls. with D\i>lo- 

 j>li>/.-( invrmix. Mediterranean. 



(4) Sub-order : Discoidece. Stem compressed 

 to a flat disc, with a system of canal-like spaces 

 (central cavity). Above lies the pneumatocyst 

 in the form of a disc-shaped reservoir of car- 

 tilaginous consistence composed of concentric 

 canals opening to the exterior. The polypoid 

 and medusoid appendages are situate on the 

 under side of the disc. In the centre is a large 

 nutritive Polyp, around which are a number of 

 smaller ones. To the base of these small Polyps 

 are attached the gonophores. The dactylozooids 

 are not far from the edge of the disc. The 

 gonophores are set free as small Medusw (Chry- 

 somitra], which do not produce the generative 

 material till long after separation. 



Fam. Velellidae. Vrlrlln xj>ir<ntx Esch.. Mediter- 

 Esch. 



FIG. 193. Part of a Di- 

 pkyid (after R. Leuck- 

 art). -D, Hydrophyl- 

 lium ; GS, genital 

 nectocalyx ; P, polyp 

 with tentacles. The 

 individual groups se- 

 parate as Emlux'iH. 



ranean. Porptta mi- 

 Order 3. SCYPHOMEDUS.E = ACALEPHA.* 



Medusce of considerable size, with gastric filaments. The edge of the 

 umbrella lobed. The sense organs covered. The embryonic stages are 

 not hydro-id stocks but ScypKistoma and Strobila forms. 



The Medusce of this order are distinguished from those of the 

 hydroid group by their considerable size and the great thickness of 



* Besides the works of Brandt. L. Agassiz, Huxley. Eysenhardt, compare 

 v. Siebold, " Beitriige zur Naturgeschichte der wirbellosen Thiere." 183U. M. 



