CEPHALOPODA. 57 



zontally ; no foot under the abdomen or throat for walking ; one 

 or more fins, without any regular order and not arranged in pairs 

 as in fishes. 



Genus 1.— PHILLIROE ; and Genus 2.— PTERO- 

 TRACHEA, are soft animals without any testaceous covering 

 or shell. 



Genus 3.— CARINARIA.— Zamarc;^. 



Generic Character — Head distinct, provided with two ten- 

 tacula, a contractile elongated mouth, and two eyes ; heart and 

 branchiae united into a single mass, projecting from the abdo- 

 men, contiguous to the tail, and enveloped in a shell ; body 

 elongated, gelatinous, pellucid, with a tail at its posterior extre- 

 mity. 



Shell univalve, conical, compressed, unilocular, extremely 

 thin, hyaline ; apex convoluted into a spire ; back, in some spe- 

 cies, forming a notched keel ; aperture oblong and entire. 



The shells of this genus are distinguished from those of the 

 Argonauta, by the spire never entering the aperture. 



Carinaria fragilis. — The Fragile Carinaria — Plate X. 

 fig. 1. Shell excessively thin, hyaline, striated longitudinally, 

 destitute of a dorsal keel. Inhabits the African seas. 



ORDER II.— CEPHALOPODA 



Head emanating from a bag-shaped mantle, and surmounted 

 by inarticulated arms ; provided with suckers, and investing the 

 mouth ; two sessile eyes ; mouth provided with two horny man- 

 dibles ; three hearts ; the sexes in separate individuals. 



Suij-DivisioN I. — Cephalopoda Sepiaria. 

 Consists of animals without any internal or external covering 

 or shell. This subdivision embraces the four genera of Sepia 

 or Cuttle fish. 



Sub-Division II. — Cephalopoda Monothalama. 

 Having unilocular shells, entirely external, and enveloping the 

 animal. 



