H4 MARINE AND FRESHWATER FISHES 



powerful sculling action of the oar-like tail, and not by the 

 aid of the pectoral fins, as in the Rays. In recognition 

 of the intermediate positions it occupies between these two 

 groups, it is in some localities distinguished by the name 

 of the Shark-Ray ; the Fiddle-fish and the Kingstone are 

 other local titles, the first suggestive of its peculiar form, by 

 which it is locally known to fishermen. Those of the Monk 

 and Angel-fish have been conferred upon it respectively 

 with reference to the fancied resemblance of the rounded 

 head and pectoral fins to a monk's hood and cowl, or of 

 the last-named structures to the wings of a seraph. As 

 acclimatised in aquaria it has been found to be an essen- 

 tially nocturnal species, reposing sluggishly on the sand or 

 shingle at the bottom of its tank, and unless disturbed 

 exercising its locomotive functions only after darkness has 

 set in. Some fine casts of this species are on view in the 

 Buckland Collection. 



DIVISION II.— Skates and Rays (Batoidei). 



Body greatly depressed ; gill-openings ventral, five in 

 number ; the pectoral fins usually enormously developed 

 around the flattened trunk ; terminating posteriorly in a 

 thin and slender tail, upon which the dorsal fins, if present, 

 are developed ; spiracles always present. 



The flattened form of the ordinary Skates and Rays 

 with their huge pectoral fins and attenuate tail is too 

 familiar to need elaborate description. Among them, how- 

 ever, are included several highly specialised types which 

 demand closer attention. As such are the Torpedoes, 

 Electric Rays, or Cramp-fishes, as they are sometimes 

 called, of which two species, the Plain Torpedo {Torpedo 

 hebetans), No. 215, and the Spotted Torpedo (T. marmorata), 



