8 AMERICAN MARINE CONCHOLOGY. 



capture by varying its tints according to the nature of the ground 

 over which it passes, and eludes its enemies, when pursued, by 

 discoloring the water around it with the contents of its ink-bag. 



Synopsis of Genera. 



Arms with two rows of cups. Body round, without fins. OCTOPUS. 

 Arms with one row of cups, bearded and united by a broad web. Body 

 finned. CIKBHOTEUTHIS. 



Genus OCTOPUS, Cuvier. 

 Regne Animal, ii. 1817. 



1. 0. RUGOSUS, Bosc. Fig. 1. 



Act. de la Soc. d'Hist. Nat., t. 15, f. 1, 2. 1792. 

 Sepia granulosa, Bosc. Buff., Vers. i. 47. 1802. 

 Sepia granulatus, Lamarck, Mem. Soc. Hist. Nat., i. p. 2. 1799. 

 Octopus Barkeri, Ferussac, Orb. Sal. Ceph. 54, No. 3. 1826. 

 Octopus Americanus, Blainville, Diet. Sc. Nat. xliii. 185. 1826. 



Body oval, purse-shaped, large, with a deep groove above. Head, 

 arms, and upper part of the body covered with roundish tuber- 

 cles. Head short, warty; ocular beard, one, elongated. Arms 

 short, thick, conical, their proportional lengths 4, 3, 2, 1. Cups 

 large, of upper part of arm rather smaller, lowest one-rowed. Web 

 short. When alive, violet-brown, white beneath ; side of the arms 

 netted with brown lines. 



North Carolina to South America ; also Indian Ocean. ? 



Genus CIEEHOTETJTHIS, Eschricht. 

 Nov. Act. Nat. Cur., xviii. 625. 1836-8. 



1. C. MULLERI, Eschricht. Fig. 2. 



Nov. Act. Nat. Cur., xviii. 1836-8. 



Body smooth, oblong, three-lobed. Fins longer than broad, 

 blunt, depressed. Eyes very small. Arms equal, quadrangular. 

 Cups very small, oval, about thirty ; beards between the cups fili- 

 form. 



Arctic America. 



ORDER DEC APOD A. 

 * Shell internal, solid, horny. 



Family LOLIGOPSID^E. Eyes naked. Mantle supported by two 

 internal fleshy bands. Siphuncle simple. Fins semicircular. 

 Family ONYCHOTEUTHID^E. Eyes naked, with a sinus above. 



