COLLEGE ZOOLOGY 



hydrozoan medusae in the absence of a velum, the characteristics 

 of the canal system, the position of the gonads, and the arrange- 

 ment and morphology of the sense-organs. 



FIG. 79. Aurclia, ventral view with two of the oral arms (or. a) removed 

 a.r.c, adradial canal; gon, gonads; i.r.c, interradial canal; mg.lp, marginal 

 lappet; mth, mouth; or. a, oral arm; p.r.c, perradial canal; s.g..p, sub* 

 genital pit; /, tentacles. (From Parker and Haswell.) 



The oral lobes or lips of Aurelia (Fig. 79, or. a) which hang 

 down from the square mouth (;;;///) are long and narrow with 

 folded margins. The mouth opens into a short gullet, which leads 

 to the sqmewhat rectangular "stomach." A gastric pouch 

 extends laterally from each side of the stomach. Within 



