C THE VOYAGE OF H.M.S. CHALLENGER. 



§ 140. Gastral genitalia of the Craspedotae. The simplest and most primitive 

 condition of the genital formation is shown in the section of the Craspedotae in such 

 genera as have only a simple reproductive organ, a circular genitalium in the subumbral 

 gastral wall, having the mouth placed in the middle. This condition is shown by the 

 Codonidae among the Anthomedusae, and also by isolated genera among the Anthomedusae. 

 The Codonidae (System, p. 10, taf. i., ii.) are distinguished by a long thin oesophagus, 

 extending in a vertical direction, in whose wall the reproductive cells are regularly 

 developed, so that the genital ring keeps the form of a cylindrical tube. In contrast to 

 this formation the Narcomedusse have a flat, broad, gastral sac, extending in a horizontal 

 direction, so that the genital ring in its subumbral wall likewise appears flat and broad 

 (Poli/colpa, PI. X. fig. 1). Whilst in many Narcomedusae, the central genital ring 

 remains quite simple, in others, it extends centripetally on to the peripheric radial 

 pouches, and in many it is finally limited to the radial pouches. It is divided into the 

 same number or double the number of separate genital pouches, which originally appeared 

 as radial canals (comp. the System der Medusen, pp. 312, 327, 335, 347, taf. xix., xx.). 

 In JEginura (Pis. XIII., XIV.), the genitalia are formed by sixteen internemal gastral 

 pouches, in Pegantlia (PL XIII. fig. 3) by a corona of separate sacs, which evaginate 

 separately into the periphery of the stomach and hang down in the separate subumbral 

 lobe cavities of the umbrella corona (PI. XL fig. 3). In most Anthomedusse the 

 originally simple genital ring (in the Codonidae) is divided in the same way, in four or 

 eight radial pieces. The radial division first takes place by the four interradial areae 

 remaining free from sexual production, whilst four perradial genitalia lie in the four 

 angles of the stomach (System, taf. iii. figs. 1,2; taf. iv. 1, &c). Each of these may, 

 however, be re-divided into two halves, which are separated by the perradial longitudinal 

 muscle of the angles of the stomach (Thamnostylus, PL I. ; System, taf. iv., figs. 3, 10). 

 Finally, these eight adradial reproductive glands may be placed near each other and 

 fused in the four interradia in such a way that the inverted limbs of each two adjacent 

 genitalia, originally separate, are connected into a single gland ; so that, finally, there are 

 four interradial genitalia in the side walls of the stomach (System, taf. v. figs. 1,3; taf. vi. 

 fig. 3, 15, &c). We have, therefore, apparently the same condition as in many Acraspedae ; 

 only in the latter, the interradial position of the four bow-shaped genitalia is a primary 

 appearance, whilst in the Craspedotae it is secondary (or rather tertiary). 



§ 141. Vascular genitalia of the Craspedotae. In antithesis to the gastral genitalia of 

 the Anthomedusse and Narcomedusae, we find in the Leptomedusae and Trachomedusae 

 the reproductive glands are usually limited to the subumbral wall of the radial canals, 

 of which they sometimes occupy the entire length, sometimes only a part of it (proximal, 

 middle or distal part). As in most Craspedotae the number of the radial canals amounts 

 to four, they are usually also four perradial genitalia (PL II.). This primitive number is 

 doubled in those Craspedotae in which four secondary interradial canals have arisen 



