56 Bulletin 47, United States National Museum. 



40. CENTROSCYLLIUM, Miiller & Henle. 



Ceniroscyllium, MULLER & HENLE, Systematische Beschreibung der Plagiostomen,191, 1838, (fab- 

 ricii). 



Teeth equal in both jaws, very small, straight, pointed, each with 1 or 

 2 smaller cusps on each side at base ; mouth crescent-shaped, with a 

 straight, oblique groove at its angle ; spiracles moderate ; gill openings 

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

 dorsal entirely behind the ventrals. One species, in the Arctic Seas. 

 (nevrpov, spine, oicvhMov, Scyllium, an allied genus, from a/ei'Mw, to rend 

 or tear to pieces.) 



75. CENTROSCYLLIUM FABBICII, (Reinhardt). 



Body covered with minute stellate ossification ; dorsal fins short, with 

 strong spines; second dorsal behind ventrals; color nearly black; Green- 

 land Seas, southward in deep water ; occasionally taken off Gloucester and 

 off the Nova Scotia Banks. (Named for Otho Fabricius, a Danish natural- 

 ist, the first to study the fishes of Greenland.) 



Spinax fabricii, KEINHARDT, Dansk. Vid. Selsk. Forh., 1828, 111, xiv, Greenland. 

 Centroscyllium fabricii, GuNTHER.Cat., vin, 425, 1870. 

 Centroscyllium fabricii, JORDAN & GILBERT, Synopsis, 16, 1883. 



Family XIX. DALATIID^E. 



(THE SCYMNOID SHARKS.) 



Sharks with no anal fin and with 2 dorsal fins, each without spine ; 

 fins all small ; gill openings small, entirely in advance of pectorals ; mouth 

 but little arched; a long, deep, straight, oblique groove on each side of 

 it ; spiracles present. Oviparous, the eggs without horny case (at least 

 in SOMNIOSUS). Vertebrae cyclospondylous. The absence of dorsal spine 

 chiefly distinguishes this family from the SQUALHXE, of which these are 

 somewhat degenerate allies. Genera, 5; species, about 10, mostly of the 

 North Atlantic, some of them reaching a large size. (SPINACID^E, part, 

 Giinther, Cat., vm, 425-429.) 



SOMNIOSIN.S: 

 a. First dorsal much in advance of ventrals. 



6. Upper teeth narrow, the lower quadrate, with a horizontal edge ending in a point 

 directed outward ; body very robust, the fins very small, the dorsals about equal ; 

 skin moderately rough. SOMNIOSUS, 41. 



41. SOMNIOSUS, Le Sueur. 



Somniosus, LE SUEUR, Jour. Ac. Nat. Sci. Phila., 1818, i, 222.(brevipinna=microcephalus). 

 Leiodon, WOOD, Proc. Bost. Soc. Nat. Hist., II, 174, 1847, (echinatummicrocephalus). 

 Ltemargus, MULLER & HENLE, Plagiostomen, 93, 1838, (borealis=microcephalus). 

 Rhinoscymnus, GILL, Proc. Ac. Nat. Sci. Phila., 1864, 264, (roslratus). 



Body thick and clumsy; mouth transverse, little arched, with a deep, 

 straight groove running backward from its angle; nostrils near the 

 extremity of the snout ; jaws feeble; teeth in upper jaw small, narrow, 

 conical ; lower teeth numerous, in two or more series, the point so much 



