64 



THE SCYPHOMEDUSAE 



or pedalia (Pericolpa) ; or four interradial tentaculocysts, four 

 perradial and eight adradial tentacles on pedalia, and sixteen 

 subradial pedalia (Periphylla). The tentacles are long and hollow ; 

 the teniaculoci/sts are short, and present on the oral face a crescentic 

 pad of pigmented sense cells, a median ocellus, and a stalked sense 

 club with otoliths ; on the aboral face lies a pair of ocelli. 



The mouth leads into a long tube, probably a stomodaeum, which 

 opens below into the gastric cavity. The latter is, as in Stauro- 

 medusae, imperfectly divided into four perradial chambers by four 

 interradial mesenteries, which are invaded by four interradial funnels 

 of the subumbrella. The mesenteries are attached to the ex- 

 umbral body wall only in the most aboral quarter of the bell, 

 and again at a point just below the union of stomodaeum and 

 gastric cavity ; there are thus left two large circular sinuses, one 

 round the subumbral funnels, the other round the edge of the bell. 

 In the pedalia at the edge of 

 the bell the circular sinus is 



3. — Haliclystns, temporarily attached 

 to a piece of weed, sliowin}; eiglit bundles 

 of capitate tentacles and eight colleto- 

 cystophores. 



4. — I'cnphjiUn mirabilis (after Haeckel). 

 The division of the exunibral surface into 

 pedalia is well shown, o, tentaculocyst 

 (interradial) ; />, suhnulial perlalia ; four 

 perradial and ei^ht adradial tentacles are 

 present. 



further subdivided into eight, si.xteen, or more pouches by fusion 

 of exumbral and subumbral walls. The phacellae are developed 

 at the sides of the mesenteries ; the genfratire organs form eight 

 horseshoe-shaped glands, jilaced adradially. 



Nothing is known of the development of this group. 



. .OuDKK .'i. Cubomedusae. 



Definition. — Scyphomedusae with foin* jierradial tentaculo- 

 cysts ; the tentacles are interradial in position. Four laminar 

 mesenteries divide the perij)heral coelenteron into four broad per- 

 radial pouches. There is no alternation of generations. 



