6 HETKROPODA. 



longitudinally grooved ; grooves unequ;il, about thirty at the anterior 

 end, but diminishing in number towards the'apex.l 'White. 

 Length, 24 ; breadth, anterior end, '3, posterior end, '05. 



Class Heteropoda. 



Foot compressed into a vertical muscular lamina, which is used as 

 a fin, or converted into a raft-like apparatus. 

 Animal free swimming. 



FA MILT I ANT -\ IN,E 



Body enclosed in a shell, foot formed into a vescicular raft, which 

 the animal can inflate at pleasure, but which cannot be withdrawn 

 into the shell. 



IANTHINA. 



Shell thin, translucent, spiral; whorls few, rather ventricose ; aper- 

 ture four-sided ; lip thin, notched at the outer angle. 

 Atlantic and Pacific Oceans. 



1. I. exiglia, Lamark; lantliina exigna, Lamarle, Anim. sans vert., 

 ix., p. 5. Whorls four, convex, rather deeply obliquely striated ; 

 mouth large ; colurnella straight, long ; outer lip deeply notched. 

 Violet, with a whitish spiral band on the posterior margin of the 

 whorls. Length, 0'4 ; breadth, 04 ; angle of spire, 85. 



Abundant on exposed sandy coasts. 



2. I. iantllina, Liimfeus; lantliina communis, Lamark, I.e., ix., 

 p. 4. Whorls four, convex, finely obliquely striated ; spire depressed ; 

 mouth large ; columella rather short, twisted to the right. Violet, 

 getting whitish on the spire. Length, 0'65 ; breadth, 082; angle of 

 spire, 107. Larger than the last, and not nearly so common. 



N. America. 



FAMILY FIROLIDJE. 



Animal cylindrical, translucent, furnished with ventral and tail fins 

 for swimming ; gills exposed on the posterior part of the back, or 

 covered by a small hyaline shell. 



CARINARIA. 



Animal large, translucent, granulated, ventral fin rounded ; tail 

 large, compressed ; gills numerous, pinnate, projecting from beneath 

 the shell, which is limpet-shaped, with a posterior sub-spiral apex, and 

 a fimbriated dorsal keel ; nucleus minute, dextrally spiral. 



Warmer parts of the Atlantic and Indian Oceans. 



* 3. C. aUStraliS, Quo//, Voij. Astrolabe, p. 394. Shell thin, 

 hyaline, transversely sulcated, apex obliquely inclined ; keel undu- 

 lated ; spire obtuse, on the right towards the whorls four elongated 

 oval apertures. Swimming foot extended, quadrilatei'al. 



