130 



COLLEGE ZOOLOGY 



hydrozoan medusae in the absence of a vdum, the characteristics 



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

 ment and morphology of the sense-organs. 



i.r.c 



-p.r.c 



FIG. 79. Aurelia, 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; t, tentacles. (From Parker and Haswell.) 



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

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

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

 to the somewhat rectangular " stomach" A mstric pouch 

 extends laterally from each side of the stomach. Within 



