SEXUAL CHARACTERS — ELASMOBRANCH FISHES 



235 



when the radii are apposed, as indicated on the (observer's) left, 

 a temporarily^ closed passage is formed. The denticles are 

 larger and differently situated, surrounding the posterior half of 

 each radius. Posterior to, and unconnected with the hypopyle, 



6-1 



5- 



Int.R. 



Cl.Gr. 



o 

 cm 



Fig. 15 Chimaera mirabilis. Ext. R. and Int. R., the external and internal 

 radii of the posterior clasper; CI. Gr., clasper groove; A., apopyle; Ant. CI., ante- 

 rior clasper; Pch., pouch of anterior clasper. 



the internal radius ends in a cartilaginous spike, and the external 

 radius in a peg, having a hole in its center from which all tissue, 

 if any, has disappeared, and surrounded by a foxglove-like 

 corolla of skin, as shown enlarged in the inset. The proximal 

 curvature of the external radius is very striking. Leading into 

 the apopyle is a ver}^ minute cavity, entirely embedded in carti- 

 lage, whose nature could only be investigated by sectioning. The 

 frontal clasper is huge in proportion to the size of the animal 

 and the spikes on it larger. 



