IV 



PHYLUM CCELENTERATA 



179 



fundibula. The gastric filaments (g. /.) are very numerous, and the elongated 

 U-shaped gonads (gon.) are eight in number and ad-radial. 



The coronary 



pr 



sr 



groove 

 teristic 



is charac- 

 of the 

 group : but in 

 other points such 

 as the number of 

 pedal and marginal 

 lobes, tentaculo- 

 cysts, and tentacles 

 there is great 

 variation. Peri- 

 colpa and its allies 

 (Peromedusce) re- 

 semble the Lucerna- 

 rida and the mem- 

 bers of the order 

 Cubomedusce in the 

 presence of tsenioles 

 and inter - radial 

 septa : EpJiyropsis 

 and its allies (Can- 

 nostomce) resemble 

 the order Disco - 

 phora in the ab- 

 sence of these 

 structures. The 

 scyphula larva of 

 Nau$ithoe(Fig. 134) 

 lives as a parasite 

 in the interior of a 

 horny sponge. 



FIG. 134. Nausithoe. The entire animal from the oral aspect. 

 ar. adradii ; g. gonads ; g.f. gastric filaments ; ir. inter-radii ; 

 m. circular muscle of sub-umbrella ; pr. per-radii ; rl. tentacu- 

 locysts ; sr. sub-radii ; t. tentacles. The black Across in the 

 centre represents the mouth. (From Lang's Comparative 

 Anatomy.) 



ORDER 3. CUBOMEDUSCE. 



The Jelly-fishes forming this order are, as the name implies, of a more or less 

 cubical form, resembling a deep bell with somewhat flattened top and square 

 transverse section. They resemble the hydrozoan Medusae more than any of 

 the other Scyphozoa. The best known species, Charybdcea marsupialis 

 (Fig. 135), is about 5 cm. in diameter and of very firm consistency. 



As in the lower Coronata, the margin of the umbrella bears four tentacles 

 (t.) and four tentaculocysts (tc.), but the position of these organs is reversed, the 

 tentaculocysts being per-radial, the tentacles inter-radial. The tentaculocysts 

 are set in deep marginal notches, and the tentacles spring from conspicuous 

 gelatinous lobes (I.), which probably answer to the pedal lobes of the preceding 

 order. These pedal lobes sometimes bear a number of supplementary tentacles. 



The margin of the umbrella is produced, in most cases but not in all, into a 

 horizontal shelf (vl. ), resembling the velum of the hydroid Medusae, but differing 

 from it in containing a series of branched vessels (end. lam'.} continuous with 

 the canal-system and of course lined with endoderm. In the Hydrozoa, it will 

 be remembered, the velum is formed simply of a double layer of ectoderm with 

 a supporting layer of mesoglcea^ Such a false velum, like the produced thin 

 edge of the umbrella in Aurelia^ is known as a velarium. 



The mouth is situated at the end of a short manubrium (mrih.} leading into 

 a wide stomach, from which go off four very broad shallow per-radial pouches 

 (rad. f).}, occupying the whole of the four flat sides of the umbrella, and 



N 2 



