66 CEPHALOPODA. 



swimming horizontally ; no foot under the abdomen or 

 throat for walking; one or more fin-like expansions, with- 

 out 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 cover- 

 ing or shell. 



Genus 3 CARINARIA Lamarck. 



Generic Character — Head distinct, provided with two 

 tentacula, a contractile elongated mouth, and two eyes; 

 heart and branchiae united into a single mass, projecting from 

 the abdomen, contiguous to the tail, and enveloped in a shell; 

 body elongated, gelatinous, pellucid, with a tail at its pos- 

 terior extremity. 



Shell univalve, conical, compressed, unilocular, ex- 

 tremely thin, hyaline ; apex convoluted into a spire ; back, 

 in some species, 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 frag'dls. — The Fragile Carinaria Plate 



X. fig. I. Shell excessively thin, hyaline, striated longi- 

 tudinally, destitute of a dorsal keel. Inhabits the African 

 seas. 



OEDER II -CEPHALOPODA. 



Head emanating from a bag-shaped mantle, and surmount- 

 ed by inarticulated arms, which are provided with suckers, 

 and surround the mouth; two sessile eyes; mouth provided 

 with two horny mandibles ; three hearts ; the sexes in sepa- 

 rate individuals. 



