266 



COMPARATIVE ANATOMY. 

 B 



So. 



ED 



FIG. 213. ABDOMINAL PORES or VARIOUS VERTEBRATES. (A, Cyclostome ; 

 B, Elasrnobranch ; C, Protopterus ; D, Spatularia.) 



A, anus ; Pa, Ra, PC, abdominal pores ; Pp, papilla ; AT, cloacal pockets ; UG and 

 a, urinogenital apertures ; L, L, lip-like margin of cloacal aperture ; CE, 

 cloaca ; DED, longitudinal folds of the rectum, which end sharply at RF ; 

 t, point at which the rectal gland opens ; BF, pelvic fin ; ft, claspers. The 

 arrow in A points towards the hcnd, and all the figures are placed similarly to A. 

 In Fig. C, Cl indicates the blind sac of the cloaca, the dorsal wall of which is 

 visible at DW '; t, the unpaired apeiture of the generative ducts ; ED, ED\ 

 the rectum, cut open. The arrow indicates the aperture of the ureters. 



