218 



W. HAROLD LEIGH-SHARPE 



RHINOBATUS PRODUCTUS 



The long-nosed skate 



This specimen (fig. 21), taken at San Diego, California, in 

 May, 1891, measures 85 cm. in length. The first point to strike 

 the observer is the extreme similitude of this species to its fossil 

 forerunner, Rhinobatus intermedins (Memoir III, p. 197). 

 The long, thin, delicate, tapering claspers with a spathe-like 

 expansion at the extremity are unmistakable, easily distinguish- 

 ing them from those of the foregoing genera. The closed portion 



•-o 



mm. 



Fig. 20 Myliobatis aquila, a transverse section of the clasper gland (hae- 

 malum-eosin). 



of the clasper tube is long, and towards the outer edge of the 

 dorsal aspect of the clasper is a slit, as in Torpedo. The claspers 

 are denticled all over, which is unusual in a skate-like form. The 

 rhipidion is narrow and elongated, and not in the form of a 

 fan; it is entirely concealed, unless the edge of the clasper tube 

 is rolled back, as in the lower inset. At the place where the 

 siphon tube debouches in Raia circularis is a well-marked sen- 

 tina, into which there is no opening from the interior. The 

 sentina is covered by an expansion resembling the web between 

 a frog's toes, and on its outer side is a non-articulate immovable 

 claw which does not resemble that of Acanthias. When the web 



