VOLUTION. 75 



dry by the tide; they are only to be procured by digging for 

 them, or when a violent storm disturbs the sand and throws 

 them on the beach.* 



The above remark is upon Australian species, but those of the 

 southern extremity of South America are also found numerously 

 in shallow water, feeding on Mytilus, etc.; nevertheless other 

 species have been dredged from great depths, as V. papillosa at 

 1900 fathoms. 



The cavity of the nucleus in a cut specimen of the shell of 

 V. vespertilio is nearly entirely filled with an amber-colored 

 pellucid calcareous deposit ; and the whole of the rest of the 

 cavity is lined with a thick glossy deposit. In a cut specimen 

 of V. Hebraea (the nucleus of which is destroyed) the cavity of 

 the upper whorl is quite filled with a white glossy deposit, and a 

 similar deposit lines the whole of the inner cavity of the shell.f 



Synopsi.v of Genera. 



* No operculum. (An operculum in V. musica.) 



CYMBIUM, Klein. Shell oval-oblong, ventricose, thin; spire short, 

 nucleus large, globular, forming an obtuse papillary apex; whorls few, 

 forming a flat edge around the nucleus; aperture oblong, wide; colu- 

 mella with several oblique plaits; outer lip thin, simple. Dentition, 

 PI. 2, fig. 2. 



MELO, Humphrey. Shell large, subovate, ventricose, thin; spire short, 

 apex obtuse, papillary, persistent; whorls smooth, the last posteriorly 

 coronated; aperture oblong, wide; columella with several oblique plaits, 

 the anterior the largest; outer lip simple, acute, obliquely truncate in 

 front. Dentition, PI. 2, fig. 3. 



VOLUTA, Linn. Shell ovate or subconical, thick, solid; spire usually 

 short; shoulder of whorls usually angulated, sometimes nodose or 

 spinous; aperture generally rather narrow; columella with a callous 

 deposit and plaited; lip generally thickened, sometimes sub reflected. 

 Dentition, PL 2, figs. 4-6. 



* * With operculum. 



[VoLUTOLYRiA, Crosse. Shell with the obconic form of Valuta, 

 longitudinally plicate; columella numerously plaited; operculate. 



Unites the form and solidity of Valuta with the smaller size and 



* Dr. J. E. Gray, Ann. Mag. N. Hist., 310, 1868. 

 tGray, Beechey's Voy., 134. 



