HISTORY OF THE FISHES OF MASSACHUSETTS. 251 



it is less valuable than whale oil to burn. It is a usual practice, however, among the 

 fishermen to mix all the common fish oils together, when they are sold in Boston market 

 under the name of shore oil. The curriers use the greater portion of this oil. This 

 species feeds upon many different kinds of fish ; but as it is generally met with while 

 following shoals of mackerel, it is generally known as the mackerel shark. At Province- 

 town, it is called blue shark. 



Maine, Massachusetts, Stoker. New York, Mitchill, Dekay. 



GENUS III. MUSTELUS, Cuv. 



Teeth blunt, forming a closely compacted pavement in each jaw ; with temporal ori- 

 fices. First dorsal in front of the ventrals. Lower lobe of the caudal short. No spines. 



Mustelus cams, Dekay. 



The Smooth Sound. 



(Plate XXXVII. Fig. 2. 2 a. Head beneath.) 



Squalus mnis, Dogfish, Mitchill, Trans. Lib. and Phil. Soc. N. Y., i. p. 486, pi. 64, fig. 209. 

 Mustelus canis, American Hound-fish, Dekat, Report, p. 355, pi. 64, fig. 209. 

 '* " Storer, Synopsis, p. 253. 



Color. All the upper part of the body is of a uniform slate color ; the sides are light- 

 er ; the abdomen of a dirty white. 



Description. Of an elongated form, gradually sloping upward from just back of the 

 eyes, to the origin of the dorsal fin, beyond which it tapers to the tail. Skin smooth. 

 The individual before me, which is a male, is three feet and three inches in length ; the 

 width of the body at the ventrals, is five inches ; the greatest height is at the origin of 

 the first dorsal fin, about three inches. The length of the head is eight and a half inches ; 

 the distance between the eyes is two and a half inches. The head is flattened between 

 the eyes, which are longitudinally oblong ; their greatest length is one inch. The tem- 

 poral orifices are just back of the posterior angle of the eyes, on a line with them. The 

 mouth is large, triangular when closed. The teeth like those of the rays. At the pos- 

 terior angle of the upper jaw, a fleshy prolongation, half an inch in length, projects 

 backward. The snout is obtuse ; the nostrils are large, situated just in front of the 

 mouth, on the edge of the base of the snout, and are covered by a valve. 



The lateral line is quite prominent throughout the greater portion of its extent, and is 

 continued in a straight course to the tail. 



