122 



COMPAEATIVE ANATOMY. 



§ 96. 



In those Medusae wWcli have no longer any relation to Hydroids, 

 the generative matters are formed in the wall of the gastro- 

 vascular system, just as in the Medusfe of the Hydroid-Polyps, 

 and the Siphonophora. These matters are generally formed in the 

 radial canals (2Equorida3), or in the pouch-like diverticula of the 

 stomach (^ginidee). When the canals are narrow the genitals form 



freely projecting diverti- 

 cula, which, when much de- 

 veloped, may have the form 

 of ruff-like folds. The 

 radial canals foi'm lamellar 

 enlargements intheGeryo- 

 nidae, when the generative 

 matters are developed. In 

 all forms the lower wall 

 of the canal, or that placed 

 away from the umbrella, 

 forms the genital region 

 (Fig. 35, f/). The germinal 

 matters in some cases reach 

 the exterior through the 

 stomach, and in other cases 

 by a rupture of the tissue. 

 In the Discophora the 

 generative organs have 

 always much the same re- 

 lations, and differ but little 

 in position and form. They 

 consist of four or eight 

 frills, curved in a semi- 

 lunar form, and arranged 

 in a rosette on the inner 

 surface of the umbrella 

 (cf . supra. Fig. 44, ov) ; 

 the frills are formed by diverticula of the gastrovascular system. 

 They are placed in depressions on the lower surface of the disc, 

 or hang fi-eely down from it, often in numerous folds. 



The Lucernarife have the generative organs in the form of eight 

 radially-arranged longitudinal ridges, placed on that part of the 

 body which corresponds to the sub-umbrella of the Meduste, where 

 they form projections into the pouches of the gastrovascular system. 

 They represent, therefore, an intermediate form between the Hydro- 

 medusse and Discophora. 



rig. 49. Diagram of a radial vertical section 

 through a sexually mature Geryonid (Carmarina 

 hastata); on the right it is taken through the 

 whole length of a radial canal, and on the left 

 through the lateral wings of a genital lamella, at 

 an interradial plane, h Marginal vesicles, c Cir- 

 cular vessel, y Generative products, h Clasp of 

 the mantle. Ic Stomach. I Gelatinous umbrella. 

 J) Stomachal stalk, r Eadial canal, s I Its inner ; 

 r s Its outer wall, u h Cartilaginous ring, v Ve- 

 lum. Z Tongue-like process (after E. Hiickel). 



