CHONDROPTERYGII. 587 



under the base, and the gill-openings all in front of the pectorals; 

 there are no pectoral orifices. Its general color is a dark slate. 

 The oil of its liver is much esteemed by curriers. The length 

 is from four to ten feet. The surface under the lens, exhibits 

 numerous minute plates; to this its generic name has reference. 



The HOUND-FISH, Mustelus canis, has blunt teeth, forming a 

 closely compacted pavement in each jaw, with temporal orifices. 

 The lower lobe of the tail-fin is short. Its length is from two to 

 four feet. 



The BASKING SHARK, Selachus maximus, has the gill-openings 

 all before the pectorals, long, and nearly surrounding the neck; 

 it has no air-holes behind the eyes; the teeth are small, of vari 

 ous forms, but generally conical. This species is over thirty 

 feet in length. It is said its liver will yield eight barrels of oil. 

 It has the popular name of Basking Shark, from its habit of con 

 tinuing for some time in one place. It is sluggish, inactive, and 

 less fierce than the other species, and inhabits the Northern seas, 

 but is occasionally seen off our coast. 



The SMALL SPOTTED DOG-FISH, Scyllium canicula, has a prom 

 inent and slightly pointed jaw, with the nostrils pierced near the 

 mouth, and a cylindrical shaped body. It keeps near the bottom 

 of the water, and feeds on fish and small crustaceans. This, and 

 the larger Dog-fish, Scyllium catulus, are found on the British 

 and French coasts. The larger species is three or four feet in 

 length, and does much damage to the fisheries on account of its 

 voracious habits. In Scotland, these fish are said to form no 

 inconsiderable part of the food of the poor. The species S. ca 

 tulus, is sometimes called the Rock-Shark. This, or a similar 

 species, is found on the coast of the United States. 



The SPINY DoG-Fisn, Spinax acanthias, (Storer,) is easily 

 recognized by the spiracles or air-holes which are placed, one 

 on each side of the temple, just behind the eye. It has a sharp, 

 strong spine in front of each of the two dorsal fins. (See Plate 

 XIV. fig. 10.) Its teeth are in several rows, small and cutting. 

 The color is slate ; the length from one to three feet. This 

 species is very numerous about Cape Cod, where they are much 

 sought for the oil which they furnish. Of the immense numbers 

 of them found in tropical seas, some idea may be formed from 

 the fact, that in the single harbor of Kingston, (Jamaica,) from 

 cne hundred to one hundred and fifty thousand are destroyed 

 annually. Twenty thousand, it is said, have been taken in a 

 seine at one time. 



The ANGEL-FISH, Squatina angelus, seems, in its form, to unite 

 t Aether the Sharks and the Rays. Swainson includes it with 



