XII 



PHYLUM CHORDATA 



335 



side and even in front of the head, so that the animal pre- 

 sents the appearance of a broad fleshy leaf. 



In all recent Elasmobranchs the male has, connected with 

 the pelvic fins, a pair of grooved appendages the claspers 

 or pterygopodia which subserve copulation. 



The mouth is situated on the ventral surface of the head, 



FIG 216. Sting-Ray (Urolophus cruciatus). (After Giinther.) 



usually a considerable distance from the anterior extremity. 

 In front of each angle of the mouth on the ventral surface 

 is the opening of one of the olfactory sacs, each of which is 

 in many forms connected by a groove the naso-buccal 

 groove with the mouth-cavity. Behind the mouth, on the 

 dorsal surface in the Rays, and laterally in the Sharks, is the 



Man. Zool. c c 



