DISCUSSION OF SPECIES AND THEIR DISTRIBUTION. 7 



tbe Atlantic. Somniosus and Echinorhinua live chiefly in mid ocean, the former unques- 

 tionably breeding at considerable depth, though it is not certain that it descends below the 

 hundred-fathom line. They are more abundant in the eastern Atlantic. 



SCYMNORHINUS, Bonaparte. 



Scymnus, (Vvier, Regne Animal, 1817, n, 130.— Mi i.i.ei: and Hkni.e, S. B. Plag., 92.— Gcnther, Cat Fish, 

 lliit. Mus., viii, 126. 



Two short dorsal tins without spine, the first at a considerable distance from the ven- 

 trals; no anal tin. Skin uniformly covered with minute scales. Mouth transverse, a deep, 

 Straight groove at each angle of the mouth. Nostrils at the extremity of the snout. Upper 

 teeth small, pointed; lower much larger, dilated, erect, triangular, not very numerous. No 

 membrana nietitans. Spiracles wide. Gill openings narrow. (Oiinther.) 



SCYMNORHINUS LICHIA, Bonaparte. (Figure 3.) 



Squalus liehia, Bonnaterre, Tahl. Encycl. tenth., 1788, 12. 



Squale liche, Lacepepe, Hist. Nat., i, 279, pi. \. fig. 3. 



Scymnus liehia, Bonaparte, Fauna Italica, m, fasc. xiv-xvi, 1836. — Mi'i.ui: and Heni.i:. s. I!. Plag.,92. — 



Dumeril, Elasm., 452. — Bocage ami Capello, l'cix. Plagioat., 34.— GONTHER, Cat. Fish. Brit. Mils.. 



\ in, 12r>. — Coi.i.i.tt, Bull. Sim-. Zi)ol. France, 219. 



A ScymniiA with seventeen or nineteen erect teeth in the lower jaw, with the edges ser- 

 iated. Scales minute, witli a median keel, and terminating in a point. The first dorsal tin 

 is nearer to the root of the pectorals than to that of the ventrals. 



Tins is the only species of the genus. It occurs in the western parts of the Mediterra- 

 nean and about Madeira. It should lie sought for by the fishermen on the Halibut banks. 



SOMNIOSUS, L.e Sueur. 



Somniosua, Le Sueur, Jonr. Acad. Nat. Sci. Phila., 1818, i, 222 (type, Somniosus hrecipinna, Le Sueur). — 



Gill, Proc. Acad. Nat. s,i. Phila., L864, 264.— Jordan, loc. <_■;/., 11. 

 Lwmargus, MOixer and Henle, s. B. Plag., 1838, 93. [Preoccupied in Crustacea by Kroyer.] 

 Rhinosoymnus (=Somnio8ti& part), Gill, '<»•. <ii. 



Scymnoid sharks with body elongate and two spineless dorsals: fins all very small, the 

 ventrals nearly opposite the second dorsal; mouth transverse, with deep groove backward 

 from its angle; nostrils near the extremity of the snout; jaws feeble: teeth in upper jaw 

 in several rows, small, narrow, conical; teeth in lower jaw numerous, in about six rows, the 

 point so miieh turned aside that the inner margin tonus a cutting edge; spiracles moderate: 

 no nictitating membrane; gill openings narrow; skin uniformly covered with line tubercles. 



Two species are known: one, S. rostratus, recorded by Bisso and Canestrini from the 

 Mediterranean, off Nice and Genoa, where, according to Canestrini, it lives at great depths 

 ( Fauna d' Italia, Pesci, p. 43); the other. 8. microcephalia, from the North Atlantic. 



SOMNIOSUS MICROCEPHALUS, (Schneider), Goode and Bean. (Figure8.) 



Squalus carcharias, MOller, Zoologies; DanicsB Prodromus, 177ii. 38 (not Liunteus). 



Squalus microcephalus, Schneider in Bloch, Syst. Ichth, 1801, 135. 



Scymnus microcephalus, Kh6ter, D aura ark's Fiske, in, ls:>:i. ml, fig. — Collett, Norges Fiske, 212. — Malm. 

 Fauna, 626. 



Sum n ins H n microcephalus, Goode and Bean, Bull. Essex [ust., 1S77. 31. — Jordan and Gilbert, Bull. \\ i. r. s. 

 Nat. Mus., 1883, 15. 



Somniosus brevipinna, Le Sueur, Journ. Acad. Nat. Sci. Phila., i, 1818, 122. — Storer, Bep. Fish. Mas-... 189. 



Scymnus brevipinna, Hi: Kay, Zool. X. v.. Fish., 361, pi. i.\i. fig. 202.— Storer, Mem. Am. Acad, s.-i.. Bos- 

 ton, ix, tsiiT, 235, pi. \\\\ in, fig. 2. 



I .n mar g us brevipinna, Dumeril, Ichth., 156, pi. v, figs. 3-4. — Moreau, Poiss. France, i. 361, fig. 63. 



Squalus borealis, Scoresby, Arctic Regions, 1820, i. 538, pi. xv, figs. 3-4. — Jenyns, Man. Brit. Vert, Anim., 

 is:::., 50b'. 



