10 AMERICAN MARINE CONCHOLOGY. 
Fins rhombic, posterior, caudal. Internal cartilage of mantle dilated below. 
Shell narrow, dilated in front with one central and two marginal ribs. 
OMMASTREPHES. 
Genus ONYCHOTEUTHIS, Lichtenstein. 
Berl. Acad. 1818. 
Body elongate, subcylindrical, smooth, acuminated behind. 
Mantle with an elongated, narrow, prominent, longitudinal ridge, 
fitting into a similar groove on the base of the siphuncle. Head 
large, rather depressed, with three to eleven longitudinal ridges, 
and edged behind by a transverse ridge. Eyes large, laterai; ses- 
sile arms angular; third or fourth pair with a keel or fin; cups in 
two alternating lines; rings convex and toothless. Tentacular 
arms partly retractile, strong; club enlarged, with a rotnded 
group of small sessile cups at each end, and two series of claw- 
like hooks, the outer series largest. Siphuncle very short, lodged 
in a cavity, with two superior muscular bands. 
1. O. Banxst, Leach. Fig. 4. 
(Loligo.) Zool. Miscel., iii. 141, sp. 4. 1817. 
Onychoteuthis Bergii, Lichtenstein, Zool. Mus. Berlin, 1592, t. 19, f.a. 1818. 
Sepia loligo, Fabricius, Faun. Greenl. 359. 
Onychoteuthis Fabricit, Lichtenstein, Isis. t. 19. 1818. 
Onyka angulata, Lesueur, Journ. Philad. Acad., ii. 99, t. 9, f 5, 184; ii. 
296, fig. 1822. 
Loligo felina, Blainy. Dict. Sc. Nat.; xxvii. 189. 1823. 
Onychoteuthis Moline, Leach, Berl. Trans., t. 4. 1818. 
Loligo uncinatus, Quoy & Gaimard, Zool. Uranie, i. 410, t. 66,.f. 7. 1838. 
Onychoteuthis Lessonii, Fer. Orb. Ceph. 61, No. 6. 1825. 
Onychoteuthis Fleurii?, Renaud. Lesson, Centurie Zool. 61, t. 17. 
Head, with eleven longitudinal, small, prominent ridges. Fins 
rhomboidal. Sessile arms unequal, in length, 2,3, 4,1. Cups 
pear-shaped. Tentacular arms very extensile, with double series 
of hooks; the basal group consisting of seven or eight open, and 
the same number of closed cups. The special group of sixteen or 
seventeen cups all open; hooks twenty to twenty-two, in two rows, 
those of the outer row largest. 
Arctic Seas to West Indies, Africa, Indian Ocean. 
2. O. Bartiinait, Lesueur. Fig. 5. 
(Loligo.) Journ. Philad. Acad., ii. 95, fig. 1821. 
Onychoteuthis Lesueurit, Ferussac, Céph. Acét., t. 4. 
