612 



MOLLUSCA 



Family 5. CEANCHIIDAE. 

 Body cylindrical; head small, with large eyes, which are without 

 cornea; sessile arms short; tentacular arms long and slender; shell 



lanceolate: 13 species. 



LoLiGOPSis Lamarck. Body elongate, 

 attenuate behind, with large fins; siphons 

 not valved : 8 species. 



L. pavo (Lesueur). Peacock squid 

 (Fig. 961). Body very long, being 1 m., 

 including tentacles; fins about one-fourth 

 the length of the body, rounded in outline; 

 color red, spotted: Arctic seas, south to 

 Cape Cod; very rare on our coasts. 



Suborder 2. OCTOPODA. 



Body more or less globose, generally 

 without fins; 8 arms, with suckers usually 

 sessile; no shell except in Argonauta; no 

 nidamental glands: about 140 species, 

 grouped in about 5 families. 



Family 1. AEGONAUTIDAE. 



Female with a tliin, symmetrical, spiral 

 shell, without septa, which is secreted by 

 terminal expansions of the two upper arms 

 and is used as an egg-case, which the animal can leave at will; male 

 very small, with the third arm on the right hectocotylized : 1 genus; in 

 all the warmer seas. 



Argonauta L. Argo- 

 naut. Paper nautilus. With 

 the characters of the fam- 

 ily: 11 species, 1 on the At- 

 lantic and 1 on the Pacific 

 coast. 



A. argo L. (Fig. 962). 

 Shell whitish, ribbed, with 

 2 rows of sharp protuber- 

 ances on the periphery, 20 

 cm. long; length of female 

 20 cm. ; color whitish or yel- 

 lowish with red dots ; length of male 25 mm. : Atlantic Ocean, occasionally 

 on the coast of the central and southern states. 



Fig. 961 — Loligopsis pavo 

 (Verrill). 



Fig. 962 — Argonauta argo. A, shell 

 without shell (Verrill). 



animal 



