GEN. SCYLLIUM. LARGE SPOTTED DOG-FISH. 301 



scarcer : the spots large and scattered, the ventrals 

 cut square at the extremity, the valves of the nos- 

 trils not approximate, as in S. canicula, but sepa- 

 rate and not reaching to the mouth. The ground 

 colour also is somewhat different, the red tinge not 

 being observable. In S. canicula, the whole of the 

 second dorsal fin is behind the anal ; in S. catulus 

 it is in a line over the lower portion of the anal. In 

 the former, the small lobe that is situated immedi- 

 ately under the outer margin of the nasal valve, is 

 of a square form ; in the latter that lobe is somewhat 

 of a triangular form and about three times broader 

 than its length, extending from the inner corner of 

 the nasal aperture along half its base, or nearly as 

 far as the posterior margin of the nasal valve ; the 

 teeth in S. catulus are about double the size of those 

 in S. canicula. * The spots are occasionally ocelli- 

 form, on which account the species has been named 

 S. stellaris by the generality of writers. It is dis- 

 posed to frequent rocky ground, and is known from 

 that circumstance by the names Rochier, Rock Dog- 

 fish. " In the Firth of Forth" says Dr. Parnell, 

 " examples are occasionally found in the salmon- 

 nets at Queensferry. It is stated by the fishermen, 

 that it is more frequently met with on some of the 

 shores further north, and at Wick specimens of 

 large size have been taken in the herring- nets; but 

 as the two species are so closely allied, it is not im- 

 probable that they have been frequently confounded. 



* ParnelFs Fishes of the Firth of Forth, p. 411. 



