360 



IIETEROPODA. CARINARIA. 



cular paddle, serving as a fin. The edge of this, in many species, 

 is somewhat dilated at one part ; forming a kind of sucker, by 

 which the animals can attach themselves, and which seems to be 

 a rudiment of the expanded foot of the Gasteropods. The gills 

 are external, and form plume-like tufts, situated at the hinder 

 part of the back. The body is gelatinous in its consistence, and 

 so transparent as to permit much of its interior organisation to 

 be seen. The mouth is furnished with a sort of muscular tube 

 or proboscis, which can be protruded or drawn in at will ; and 

 it contains a rasp-like tongue. One of the most remarkable 



----_.-. !' 



FIG. 553. CARINARIA ; a, mouth ; b, tentacula ; c, eyes ; d, stomach ; , gills ; /, anus ; 

 g, shell ; h, liver ; i, foot ; k, sucker. 



genera of this group, is the Carinaria ; which possesses a thin 

 shell, not unlike that of the Argonaut in form ( 890). This 

 shell protects the heart and liver ; the gills float around its edge, 

 and the intestinal canal terminates in its interior. All the known 

 animals of this group are inhabitants of the warmer-temperate, 

 and tropical seas ; many of them are found in the Mediterranean. 

 Their general form and structure correspond very closely with 

 those of the Carinaria. 



