SEXUAL CHARACTERS — ELASMOBRANCH FISHES 



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The external radius, which is capable of flexion outwards to 

 prevent ehsion from the oviduct, is denticled at the tip on the 

 outer border, and all along the inner border, while the more 

 stationary internal radius is denticled all along its outer margin 

 which is grooved, the denticles being represented by stippling 

 in the figure. The two radii, when approximated, together form 

 a clasper groove or tube suggestive of the elasmobranchs. The 

 whole external radius is therefore analogous in function to the 



Fig. 3 Chimaera monstrosa. A7U. cl., anterior clasper partly protruded; 

 Pch., pouch with anterior clasper retracted; Ex. R. and Int. R., the external and 

 internal radii of the posterior clasper; 0. C, opening of cavity; A., apopyle. 



spur in Acanthias, the radii being long and slender and apparently 

 not erectile. 



Leading into the apopyle is a cavity which I cannot consider 

 the homologue of the siphon for the following reasons: 1) It 

 does not appear to be a smooth sac with muscular walls; 2) it is 

 situated in the swollen proximal end of the clasper, and not on the 

 ventral surface of the abdomen; 3) part of the skeleton of the 

 clasper (the basal portion from which the two radii originate) has 

 to be cut through to reveal its interior, which is not the case in 



