REPORT ON THE DEEP-SEA MEDUSA. ciii 



cathammal septum belonging to them, but in two different perradial pouches, so that each 

 pouch contains the inverted halves of two adjacent pairs of genitalia. In the Luccrnaridse 

 (Pis. XVI.-XVII.) and in the Peromedusse (Pis. XVIII.-XXV.) the eight reproductive 

 glands, which are connected in pairs, lie as leaf-shaped swellings in the subumbral wall of 

 the four perradial pouches themselves. In the Cubomedusaa (PI. XXVI.), on the other 

 hand, they are only connected with the four perradial pouches by a narrow marginal 

 insertion (immediately next to the fused streak of the cathamma but on its subumbral 

 side), and otherwise project as eight free genital leaves into the hollow space of the 

 pouches, of which they occupy the larger part (fig. P, s ; System, taf. xxi.-xxvi.). In the 

 different Tesseroniae we find many stages of development in the structure of the 

 genitalia. In the simplest case, in the Tesseridse, the sexual glands are merely simple 

 ridges or pads, originated by wheel-shaped thickenings of the endoderm of the subumbral 

 wall (like the most simple vascular genitalia of the Craspedotse) ; a corresponding ridge 

 of the fulcral lamella serves as supporting frame (" sterigma ") for the subepithelial 

 germinal cells. Further (in part of the Peromedusse), more or less complicated folds are 

 formed, which rise above the subumbral wall and project freely into the space of the 

 pouches ; the supporting frame of the fulcral plate (" sterigma ") likewise rises higher 

 and attains greater development (Pis. XXIII. fig. 38, 39 ; Pis. XXV. fig. 5-7). In the 

 Cubomedusse the sterigma is developed into a broad, thin leaf, which is only connected 

 with the supporting plate of the subumbrella at the base of insertion (near the cathammal 

 ridge), and bears sexual cells on both its free surfaces (axial as well as abaxial) ; its freer 

 margin is sometimes lobed or branched dendritically (Chirodropus, System, taf. xxvi.). 

 The reproductive glands attain their most complicated structure in the Lucernaridse 

 (System, p. 386). Each of the eight reproductive leaves is here divided into numerous, 

 separate follicles, each containing a genital sinus with excretory passage, and each follicle 

 is sometimes again composed of a number of smaller sacs (PI. XVII. figs. 17-19). 



§ 144. Gastral genitalia of the Acraspedse (Ephyronias). Whilst in all Tesseronia? the 

 subumbral wall of the four perradial pouches is the place of origin of the reproductive 

 glands, in the Ephyroniae or Discomedusse it has migrated centripetally from the pouch 

 wall to the subumbral wall of the central stomach. This centripetal change of locality must 

 therefore be phylogenetically considered as secondary, since the younger and more highly 

 developed Ephyronise are clearly derivable from the older and more simply constructed 

 Tesseroniae, and since the lowest and oldest grades of development of the former present 

 points of connection with the latter. In some Cannostonise (especially some Ephyridse) 

 in which the four primary interradial cathammal nodes are still preserved, we still find 

 four interradial horseshoe-shaped genitalia, which enclose the nodes by their concave 

 proximal arches and whose distal diverging limbs still lie in the subumbral wall of the 

 coronal sinus or of the four perradial pouches (System, pp. 467, 480, 492 ; taf. xxvii., 

 xxviii., xxix.). The pairs of limbs are here often divided into separate halves, as the 



