Cll 



THE VOYAGE OF H.M.S. CHALLENGER. 



or to the subumbral wall of the broad, flat central stomach, so that they here appear 

 again as gastral genitalia. Another still more important distinction between the two 

 sections consists in the fact that in the Craspedotae the four radial pieces of the 

 reproductive apparatus lie originally perradially, whilst on the contrary, in the Acraspedae 

 they lie originally interradially. Whilst in the Ephyronige, among the Acrasj:>eda3, there 

 are usually four interradial glands (more rarely divided into eight pieces), in the 

 Tesseroniae, on the contrary, there are usually eight separate pieces, which, however, 

 always belong in pairs to the four interradial genitalia. 



§ 143. Bursal genitalia of the Acraspedae (Tesseroniae). In all Tesseroniae the 

 central stomach remains free from the sexual productions, and the reproductive glands 

 are exclusively, or for the most part, developed in the subumbral wall of the four 



Fig. P. Proc/iaragma prototypus (Cubomeduss, Charybdeidae). 



Horizontal transverse section below the stomach, whose subumbral wall (gc) is completely visible, in 

 the middle, the oral opening («) with the four perradial oral lobes (al). The gastral filaments (/) 

 are placed upon the four interradial pyloric valves [gy). (gic) Subumbral wall of the two gastral 

 pouches (bp). (*) Genitalia, (ug) Gelatinous substance of the umbrella. 



perradial pouches. In the most simple case, four interradial horseshoe-shaped glands 

 are formed, which include the four interradial cathammal nodes (hi) or the proximal ends 

 of the four narrow septal ridges (ks) in the concavity of their U-shaped proximal ends, 

 whilst the two limbs of each arch project into the two adjacent perradial pouches (PL 

 XV. figs. 2-6). The oldest and simplest of all Acraspedae, the Tesseridae (System, taf. 

 xxxi.), and some of the closely allied Lucernaridae (Halicythus), show this most simple 

 and apparently original condition. In all other Tesseroniae (and also in most Lucernaridae 

 and in all Peromedusae and Cubomedusae) each of the four interradial genitalia is divided 

 into two separate halves, as the convex proximal ends of the horseshoe-shaped gland (which 

 encloses the cathammal nodes) have undergone retrograde formation and disappeared, 

 so that only the two limbs remain. These lie on the two sides of the interradial 



