16 CONTRIBUTIONS TO NORTH AMERICAN ICHTHYOLOGY IV. 



lO.— CE]VTROSCYi,L.IU]n[ Muller & Henle, 1837. 



BlacTc Dog-fishes. 



(Miiller & Henle, Systematisclie Beschreibung der Plagiosto'men, 191 ; type Spinax 

 fahricii Reinhardt. ) 



Teeth equal in both jaws, very small, straight, pointed, each with one 



or two smaller cusps on each side at base ; mouth crescent-shaped, with 



a straight, oblique groove at its angle ; spiracles moderate ; gill-oj)en- 



ings rather narrow ; dorsal fins small, each with a strong spine ; the 



second dorsal entirely behind the ventrals. One species, {-/.ivrpov, spine ; 



arJAlurj^ ScyUiiim^ an allied genus, from avJAXu)^ to rend or tear to pieces.) 



15.— C. fabricii (Reinhardt) M. &, B..— Blade Dog-fish. 



Body covered with minute stellate ossifications ; color dark brown. 

 A shark of the Greenland Seas, lately taken off Gloucester, Mass., by 

 the United States Fish Commission. 



^{Spinax fahricWRemhaTdt, Dansk. Vid. Selsk. Fork. 1828, iii, xvi; Giinther, viii, 425.) 



11.— SQUALUS LinnsBus, 1758. 

 Dog-Jishes. 

 (Acavthias Risso.) 

 (Artedi, Liniia>ns, Systema Naturaj ; type Squalus acanthias L.) 



Body rather slender ; mouth little arched, with a long, straight, deep, 

 obUque groove on each side ; no labial fold along the margin of the 

 mouth ; teeth rather small, equal in both jaws, their points so much 

 turned aside that the inner margin forms the cutting edge ; si)iracles 

 rather wide, just behind the eye ; gill-openings narrow, in front of the 

 pectorals ; fins moderately developed, the first dorsal larger than second, 

 much in advance of the ventral fins, which are behind the middle of the 

 body, although in advance of the second dorsal. Small sharks, abound- 

 ing in the Temperate Seas. (Latin, sqnalits, a shark.) 

 * Dorsal spine not grooved ; its insertion rather behind inner angle of the pectorals. 

 16. — S. siCiiBBtBuJas L. — Pklccd Dog-fish ; Dog-fish; Bone Dog ; SMttle-dog ; Hoe. 



Body slender ; snout pointed 5 head 6 J in length 5 depth about 8 ; 

 slate-color above, pale below, back with whitish spots, especially in the 

 young. L. 1 to 3 feet ; weight 5 to 15 pounds. 



A small sharp-toothed shark, ranging widely in the Atlantic, very 

 abundant along the shores of the Northern and Middle States. It is 

 somewhat valued for its livers, from which " Dog-fish" oil is extracted. 

 American writers have usually considered our species {Squalus ameri- 



