COPULATORY ORGANS 



487 



In addition to pelvic claspers essentially similar to those of 

 other Elasmobranchs (the distal part in Chimsera being subdivided 

 and covered with numerous dermal denticles) the Holocephali 

 possess a pair of curious anterior claspers (Fig. 365), which are 

 protruded from a shallow pouch situated in front of the pelvic 

 fins: each of these consists of a plate covered with dermal 

 denticles, and in Callorhynchus a grooved structure is present in 

 addition. There is also a knob-like organ, usually known as the 

 frontal clasper, on the upper surface of the head (Fig. 66). 



Amongst Amphibians, the very muscular cloaca in the 

 Gymnophiona can be extruded to a length of 5 centimetres, and 

 thus serves temporarily as a kind of copulatory organ. 



Two kinds of copulatory organs are found in Reptiles, the one 

 being seen in Lizards and Snakes, and the other in Chelonians and 

 Crocodiles. In the former there are two copulatory sacs or penes 



FK;. 36(3. COPULATORY ORGANS OF La<:trfa ayi/i-y. (After F. Leydig. ) In A 

 they are shown everted, and in B their position in the retracted condition is 

 indicated by dotted lines extending backwards from the vent, 

 vent : R, R l , penes ; SD, the so-called femoral pores (see p. 23) ; t, spiral 

 farrow. 



lying outside the cloaca, under the skin at the root of the tail, and 

 these can be everted and protruded through the vent, and again 

 withdrawn by means of a muscle inserted into the blind end of 

 the sac (Fig. 366). In its everted condition, a spiral furrow 

 extends along each sac down which the seminal fluid passes. 

 These organs, which show 110 cavernous structure, are also repre- 

 sented in the female, in which, however, they are much smaller. 



In Chelonians and Crocodiles the penis is single, and corre- 

 sponds to a thickened portion of the anterior lip and ventral wall 

 of the cloaca (Figs. 367, 368, A). It consists of fibrous and caver- 

 nous (erectile) tissue and is protrusible, and definite protractor and 

 retractor muscles occur in Chelonia similar to those in Ratite Birds. 

 In the female it is represented by a smaller clitoris. The penis 

 bifurcates proximally, and its distal tongue-shaped portion ends 

 freely; a longitudinal groove extends along the upper surface, at 



1 I* 



