320 PLAGIOSTOMATA. 



B. Dorsal fins spineless. 

 Genus III L^margus,* Milller and HenJe. 



Dalatias, Rafinesque. Scymnus, sp. Cuvier (1817). Somniosus, Lesueur, and 

 Bhinoscymnus, Gill. 



Spiracles present. Mouth transverse, with a deep groove at its angle. No nicti- 

 tating membrane to eye. Teeth conical and in several roivs in the upper jaw ; 

 flattened, with smooth edges, and in about six rows in the lower jaw ivith the points so 

 'turned aside that the lateral margin forms the cutting edge. All the fiyis comparatively 

 small : two spineless dorsals. Gill-openings narrow. Shin with fine tubercles. 



Geographical distribution. Northern seas, extending to temperate ones. 



1. Lffiinargus microcephalus, Plate CLXII, fig. 1. 



Squalus carcharias, Mull. Prod. Zool. Danm. p. 38 (not Linnaeus). 



Squalus microcephalus, Bl. Schn. p. 135. 



Somniosus brevipinnis, Lesueur, Journ. Ac. Nat. Soc. Phil. 1818, i, p. 222 ; 

 Storer, Rep. Fish. Mass. p. 189. 



Squalus borealis, Scoresby, Arct. Reg. 1820, i, p. 538, pi. xv, f . 3, 4 ; Jenyns, 

 Manual, p. 506. 



Scymnus borealis, Flem. Brit. An. p. 166; Yarrell, Brit. Fish. (ed. 1) ii, p. 

 403, c. fig. (ed. 2) ii, p. 527 ; Swainson, Fishes, ii, p. 315 ; Nilss. Skand. Fauna, 

 iv, p. 724 ; Thompson, Nat. Hist. Ireland, iv, p. 255. 



Scymnus glacialis, Faber, Fisch. Isl. p. 23 ; Nilss. Prod. Ich. Skand. p. 116. 



Scymnus gunneri, Richards. Faun. Brit.-Amer. iii, p. 313. 



Squalus norwegianus, Blainv. Fauna France, p. 61 ; Gronov. ed Gray, p. 8 

 (norvegicus). 



Scymnus micropterus, Yal. Nouv. Ann. Mus. 1832, i, p. 454, pi. xx. 



Scymnus (Lannargus) borealis, Mull, and Henle, p. 93. 



Lcemargus borealis, Bonap. Cat. Met. p. 16 ; Gaim. Voy. Green. Poiss. pi. xxii ; 

 Yarrell, 1. c. (ed. 3) ii, p. 524 ; Dumeril, Ich. i, p. 455, pi. v, f. 1, 2 (teeth) ; 

 Gunther, Catal. viii, p. 427. 



Leiodon echinatum, Wood, Proc. Bost. Soc. Nat. Hist ii, p. 174. 



Scymnus brevipinna, De Kay, New York Fauna, Fish. p. 361, pi. Ixi, f. 202 ; 

 Storer, Mem. Amer. Acad. 1867, ix, p. 235, pi. xxxviii, f. 2. 



Scymnus microcephalus, Kroyer, Danm. Fisk. iii, p. 914, c. fig.; Malmgren, 

 CBfv. Sven. Vet.-Ak. Forh. 1864-65, p. 536; Collett, Norges Fiske, p. 212; 

 Winther, Prod. Dan. Mar. p. 59 ; Malm, Fauna, p, 626. 



Dalatias microcephalus, Gray, Chond. Fish. p. 76 ; White, Catal. p. 132. 



Laimargus brevipinna, Dumeril, 1. c. p. 456, pi. v, f . 3, 4 ; Moreau, Poiss. de la 

 France, i, p. 361, f. 63. 



Greenland shark, Couch, Fish. Brit. Isles, i, p. 57, pi. xiii. 



The body is largest in circumference just behind the pectoral fin ; the head is 

 rather large, snout much smaller in circumference than is the head just behind it. 

 Mouth transverse, arched, its angle being about midway between the end of the 

 snout and the fourth gill-opening. Eye small and placed above the angle of 

 the mouth ; spiracle some little distance behind and above the orbit. Nostril 

 near the end of the snout. Gill-opening small, the last being before the base 

 of the pectoral fin. Teeth rather narrow and conical in the upper jaw and 

 in six or seven rows, in the lower jaw flattened, with the point turned aside, as 

 described in the generic definition. In the skull of a specimen 14| feet long, 

 from Aberdeen, there are three rows anteriorly, including the one in use in 

 the upper jaw, but the lower of these rows is deficient opposite the symphysis. 



* Preoccupied in Crustacea b\ Kroyer. 



