Lamarck's Genera of Shclh. 63 



spire crowned with arched, pointed, nearly straight spines ; colu- 

 mella triplicate. Asiatic Seas. PI. v. Fig. 200. 44 Recent spe- 

 cies, and 18 fossil. 



4. Marginella*. 



Shell oblong oval, smooth; spire short; right lip externally 

 varicose ; base of the aperture very slightly notched. Columella 

 plaited ; plaits nearly of equal size. 



The marginellse are generally smooth, polished shells, prettily 

 coloured, and remarkable for the varix, or projecting callus on the 

 right lip of the aperture. They are distinguished from the mitree 

 and voluta; by the equal folds on the columella, by the aperture, 

 which almost always occupies the whole length of the shell, by the 

 pallus on the right lip, and by the scarcely perceptible notch at the 

 base of the aperture. They inhabit the seas of warm climates. 



Lamarck subdivides the genus into, 1, shells with a projecting 

 spire ; and, 2, those without a projecting spire. 



Type. Marginella glabella^. (Voluta glabella. Linn.) 



Shell ovate oblong, grayish yellow, surrounded with reddish 



zones, sprinkled with very small white spots ; spire short, conical ; 



apex obtuse; columella quadriplicate. Senegal. PI. v. Fig. 201. 



25 Species. 



5. VolvariaJ. 



Shell cylindrical, convolute ; spire scarcely projecting. Aper- 

 ture narrow, as long as the shell. One or more plaits on the lower 

 part of the columella. 



Distinguished from marginella by having, in general, no varix 

 on the outer lip, which is thin and sharp, though sometimes slight 

 traces of a varix are perceptible. The volvarije are all sea shells, 

 and generally of small size. 



Type. Volvariabulloides§. 



* From murgo, a margin, in allusion to the varix on the right lip. 



f Dim. from glaber, smooth, or bare. J From volvo, to roll. 



§ Like a bulla. We have chosen this, though fossil, and the last of La- 

 marck's species, for our type, as most perfectly answering the characters of 

 the genus, and as being the individual on which he originally established it. 

 Sec his System, isoi. 



