3i8 



COELENTERATA SCYPHOZOA 



remarkable example of this mode of reproduction (Fig. 144), as ifc 

 forms an elaborate branching colony in the substance of certain 

 species of sponges. The ectoderm secretes a chitinous perisarc, 

 similar to that of the hydrosome stage of many of the Hydrozoa, 

 and consequently Stephanoscyphus {Spongicola), as this Scyphi- 

 stoma was called, was formerly placed among the Gymnoblastea. 

 It is remarkable that, although the Scyphozoan characters of 

 Spongicola were proved by Schulze ^ in 1877, a similar Scyphi- 

 stoma stage has not been discovered in any other genus. 



Order I. Cubomedusae. 



Scyphozoa provided- with four perradial statorhabs, each of 

 which bears a statolith and one or several eyes. There are four 

 interradial tentacles or groups of tentacles. The stomach is a 



large cavity bearing four 

 tufts of phacellae (Fig. 145, 

 Ph), situated interradially. 

 There are four flattened 

 perradial gastric pouches 

 in the wall of the umbrella 

 which communicate with 

 the stomach by the gastric 

 ostia {Go). These pouches 

 are separated from one 

 another by four interradial 

 septa ; and the long leaf- 

 like gonads are attached 

 by one edge to each side 

 of the septa. In many 

 respects the Cubomedusae 



Fig. 145.— Vertical section in the interradial plane appear tO be of simple 

 of Tripedalia cystophma. Go, Gastric ostia ; structure, but the remark- 

 Man, manubrium ; Ph, group of phacellae ; , , , . „„ . . „ , 



able dinerentiation oi the 



(After eygg and the occurrence of 



a velum (p. 313) suggest 



that the order is a highly specialised offshoot from a primitive stock. 



Fam. 1. Charybdeidae. — Cubomedusae with four interradial 



tentacles. 



T, tentacles in four groups of three ; Unt, 

 perradial sense - organs ; V, velum. 

 Conant. ) 



^ Archiv. Mikr. Anat. xiii. 1877, p. 795. 



