552 



RAIIDE. 



are young, the teeth in both sexes arc alike broad and flat ; 

 but as the male acquires age and sexual power, the teeth that 

 are nearest the centre begin to alter in form and become 

 pointed, as will be seen on close examination, by an elonga- 

 tion of the internal angle ; all the points being directed back- 

 wards or towards the throat. Some exceptions to this appa- 

 rent rule will be pointed out. 



Another sexual peculiarity in which the Skate resemble 

 the Sharks is the cylindrical appendage to each ventral fin in 

 the males. The figure at the head of this subject is taken 

 from the under surface of a female, in which no appendages 

 exist ; the second figure of the Sharp-nosed Skate, the next 

 in succession, is from the upper surface of an old male, and 

 appendages lying on each side close to the tail may be seen ; 

 even in very young specimens, not more than three inches in 

 breadth, the sexes may be determined by the constant exist- 

 ence of these appendages in the males. The fourth figure is 

 taken from the under surface of a vouno 1 male, and exhibits 



v O 



these appendages of smaller size : their use may be inferred 

 from the name they bear they are commonly called claspers. 

 The second figure of the Sharp-nosed Ray exhibits also other 

 peculiarities common to males : these are the clusters of spines 

 outside the eye and temporal orifice on each side, and the 

 regular rows of spines towards the upper outer surface of the 

 pectoral fins. The elongation of the central teeth, the devc- 



