502 PISCES (CARTILAG.) PLAGIOSTOMI. [SQUALUS. 



duced, of a somewhat triangular form, very much flattened, and in front 

 of the nostrils somewhat pellucid : nostrils beneath, nearly midway be- 

 tween the mouth and the extremity of the snout, partly covered by a 

 small membranous flap: mouth wide : jaws moderately bent: teeth small, 

 sharp-pointed, of a triangular form, with some smaller denticulations on 

 the outer edge only ; in several rows, and nearly similar above and below : 

 eyes about half-way between the end of the snout and the first branchial 

 opening ; behind each a small temporal orifice : branchial openings five 

 in number, rather small, near together ; the first four of nearly equal 

 size; the fifth smaller, and placed immediately above the base of the 

 pectoral: skin moderately rough from tail to head, but smooth in the 

 opposite direction : two dorsals : the first not very large, commencing at 

 exactly one-third of the entire length; its height and length about equal; 

 of a triangular form, but with a projecting point at its posterior extremity 

 directed towards the tail: second dorsal just half-way between the first 

 and the extremity of the tail; of a similar form, but smaller: anal pre- 

 sent, resembling the second dorsal ; nearly opposite to that fin, but placed 

 a little backwarder : caudal with a large projecting lobe on its lower 

 margin; the upper lobe terminal, and obliquely truncated at its ex- 

 tremity : pectorals moderate, approaching triangular, the distance from 

 their insertion to the end of the snout considerably more than equal 

 to their length : ventrals exactly in the middle of the entire length, and 

 answering to the middle of the space between the two dorsals ; only half 

 the size of the pectorals, and obliquely truncated at their extremities. 

 (Colours.) Of a uniform deep slate-gray above; yellowish white beneath. 

 Common in the Mediterranean, but apparently of not very frequent 

 occurrence in the British seas. Willughby speaks of its being met with 

 on the Cornish coast, where it has been since observed by Mr. Couch. 

 Pennant's specimen was taken on the coast of Flintshire," and weighed 

 twenty-seven pounds, its length being five feet. Dr. Johnston has pro- 

 cured it on the coast of Berwickshire*. The individual described above 

 was obtained, with others, at Weymouth, by Professor Henslow. Accord- 

 ing to Bloch, it sometimes attains to the weight of one hundred pounds. 

 It is stated by this same author, that it usually lives in society, and in 

 deep water. 



(5. MUSTELUS, CUV.) 



192. S. Mustelus, Linn. (Smooth Hound.) 



S. Mustelus, Linn. Syst. Nat. torn. i. p. 400. Turt. Brit. Faun. 

 p. 112. Blainv. Faun. Franc, p. 81. pi. 20. f. 1. Mustelus 

 Isevis, Will. Hist. Pise. p. 60.' tab. B. 5. f. 2. Flem. Brit. An. 

 p. 166. Galeus Mustelus, Leach in Wern. Mem. vol. n. p. 63. 

 pi. 2. f. 3. Smooth Hound, Penn. Brit. Zool. vol. in. p. 116. 

 pi. 16. Smooth Shark, Id. (Edit. 1812.) vol. in. p. 151. Tope 

 Shark, Id. pi. 18. L'Emissole commune, Cuv. Reg. An. torn. n. 

 p. 390. note (1). 



LENGTH. From three to four feet; sometimes more. 



DESCRIPT. (Form.) General form very similar to that of the S. 

 Galeus ; the snout, however, not quite so much produced : nostrils 

 midway between the mouth and the end of the snout, partly covered 

 by a small cutaneous membrane: teeth small and numerous, obtuse, 

 forming a closely compacted pavement, disposed in a quincuncial order : 

 eyes large, oval : behind each a temporal orifice of moderate size : 



* Proceed, of Berwicksh. Nat. Club. p. 7. 



