5 1 6 Memoir Sears Foundation for Marine Research 



Tentative Key to Northern Hemisphere Species 



la. Origin of ist dorsal much nearer to tip of snout than to tip of caudal; interspace be- 

 tween 1st and 2nd dorsals at least as long as from snout to ist or 2nd gill opening. 

 2a. Distance from tip of 2nd dorsal to origin of caudal nearly or quite as long as 

 base of 2nd dorsal; base of ist dorsal only Yi to Y^ as long as distance from tip 

 of snout to origin of pectorals; no evident luminescent organs. 



mkrocephalus Bloch and Schneider, i8or, p. 516. 



2b. Distance from tip of 2nd dorsal to origin of caudal only about V2 as long as base 



of 2nd dorsal; base of ist dorsal nearly or quite Yz as long as from tip of snout to 



origin of pectoral; adult with luminescent dots. rostratus Risso, 1 826. 



Mediterranean; probably 

 Portugal. 



lb. Origin of ist dorsal almost as near to tip of caudal as to tip of snout; interspace between 

 1st and 2nd dorsals only about % as long as from tip of snout to 2nd gill opening. 



pacificus Bigelowand Schroeder, 1944. 



Japan, probably also Bering Sea and Alaska, south 

 to Puget Sound and occasionally to southern 

 California. 



Somniosus mkrocephalus (Bloch and Schneider), 1801 



Greenland Shark, Gurry Shark 



Figures lOO, lOi 



Study Material. Excellent mounted specimen, 10 feet long, from Upernavik, West 

 Greenland (Amer. Mus. Nat. Hist.) and old mount of a specimen 1,740 mm. (Harv. 

 Mus. Comp. Zool.) ; jaws of Gulf of Maine specimen, about 1 1 feet (Harv. Mus. Comp. 

 Zool.) ; lower jaw, from a Grand Banks specimen, taken at Lat. 43° 11' N., Long. 51° 22' 

 W. (U.S. Nat. Mus., No. 26270) ; excellent photographs of an i i-foot specimen;" also a 

 fresh-caught specimen of 10 to 11 feet from Cape Cod Bay examined by us in the flesh 

 some years ago.'" 



Distinctive Characters. The adult Greenland Shark is so large that it could not be 

 confused with any other Atlantic squalid. Its lack of dorsal fin spines further marks it off 

 from the members of Squalus, Centra scyllium and the pigmy genus Etmopterus among 

 local genera. Its quadrate lower teeth with strongly oblique cusps separate it sharply from 

 Dalatias and Isistius, and its dermal armature sets it off from Centroscymnus (cf. Fig. 

 lOi B with 94 A). The forward position of its first dorsal, the shape of its teeth in general, 

 its dermal denticles, the shape of its caudal and its much smaller gill openings separate it 

 from Echinorhinus. 



9. Contributed by F. E. Firth. 



10. We have examined the Japanese specimen mentioned above, the lower jaw of one found on the beach near St. 

 Michaels, Alaska, and the head of another from California loaned by the U.S. National Museum, 



