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



Among the Craspedotae the so-called excretory papillae or subumbral papillae (also termed 

 marginal funnels or excretory funnels, "papillae excretoriae" or "subumbrales") belong to this 

 category. These peculiar excretory organs of the umbrella margin are found exclusively 

 in the order of the Leptomedusae, among which, however, they are tolerably wide spread. 

 They are small funnel-shaped or conical warts, which project in different numbers, on the 

 distal margin of the subumbrella between the margin of insertion of the velum and the 

 circular canal : they contain an evagination of the circular canal and open by a small 

 aperture into the umbrella cavity (System, p. 119, taf. xi. fig. 13, ex; taf. xiii. fig. 5, q). 

 Their number in many Eucopidae (e.g., Octorchis) and iEquoridae (e.g., Polycanna) is very 

 considerable but indefinite. The flagellate cells of the endoderm in the subumbral papillae 

 are directed externally towards the marginal pore, so that the latter must be regarded 

 as an "excretory opening" or "anus." Among the Acraspedae, similar marginal axial 

 openings have been long known in Aurelia, where they lie at the distal end of the eight 

 adradial canals, where the latter open into the coronal canal ; the ejection of fluid by these 

 canals can be easily observed directly in the eight adradial marginal pores. These pores 

 also occur in other Ulmaridae. As, however, they are small and easily overlooked, it is 

 possible that they are much more widespread than we are aware of at present. In some 

 Medusae, the tentacles seem also to have an opening at the distal end. 



§ 137. Reproductive organs (" gonades, genitalia, sexualia," s). In all Medusae the 

 reproductive organs show very simple, homologous, and uniform conditions of formation, 

 inasmuch as they everywhere consist essentially of reproductive glands (" gonades "), and 

 are universally developed in the subumbral wall of the gastrovascular system. The two 

 sexes show no essential difference, as the male spermaria develop in the same places, and 

 in the same way as the female ovaries. On the other hand, there is an essential and 

 thorough distinction between the two sections of the class Medusae, inasmuch as the 

 subepithelial layer of cells, which, as sexual epithelium or germinal epithebum, furnishes 

 the two kinds of sexual cells, the spermatozoa, and the ova, belongs to the ectoderm in the 

 Craspedotae, to the endoderm in the Acraspedae. In the former, the mature reproductive 

 elements are therefore emptied immediately outside into the ectodermal umbrella cavity, 

 whilst in the latter they first pass into the endodermal hollow space of the gastrovascular 

 system, from which they are ejected by the mouth. The Craspedotae are therefore 

 Ectocarpae, like the Hydropolyps, Siphonophorae, and Ctenophorae, whilst the Acraspedae 

 are Endocarpae, like the Scyphopolyps and Corals (§ 19). 



§ 138. Gonochorism and Hermaphroditism. Nearly all known Medusae are of separate 

 sexes, gonochoristic, only a very few are hermaphrodite. The Pelagic Chrysaora certainly 

 belongs to the latter (System, p. 503, taf. xxxi.). Here, whilst the four interradial 

 genitalia produce ova, roundish spermaria or testes-like sacs are simultaneously formed in 

 very irregular number on the most varied parts of the sumbumbral wall of the gastro- 

 vascular system, both in the genitalia, and on the oral arms, and also on different parts of 



