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, Liechtenstein. 

 Berl. Acad. 1818. 



Bod}' 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, lateral; 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 rounded 

 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. 0. Banksii, Leach. Fig. 4. 



{Loligo.) Zool. Miscel., iii. 141, sp. 4. 1817. 



OnychoteutMs Bergii, Licbtenstcin, Zool. Mas. Berlin, 1592, 1. 19, f. a. 1818. 



Sepia lolfgo, Fabricius, Faun. Greenl. 359. 



Onychoh /'(his Fabricii, Liechtenstein, Isis. t. 19. 1818. 



Onyka angulata, Lesueur, Journ. Philad. Acad., ii. 99, t. 9, f. 3, 184 ; ii. 



29G, fig. 1822. 

 Loligo f, Una, Blainy. Diet. Sc. Nat.; xxvii. 139. 1823. 

 Onychoti I't/iis MoUnce, Leach, Berl. Trans., t. 4. 1818. 

 Loligo uncinatus, Quay & Gaimard, Zool. Uranie, i. 410, t. 66, f. 7. 1838. 

 Onychoteuthis Leasonii, Fer. Orb. Ceph. 61, No. 6. 1825. 

 Onychotcuthis Fleurii, Renaud. Lesson, Centime 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. 0. Bartlingii, Lesueur. Fig. 5. 



{Loligo.) Journ. Philad. Acad., ii. 95, fig. 1821. 



Onycliotcuthis Lesueurii, Ferussac, Ceph. Acet., t. 4. 



