GENUS DOLIUM. J3 



these ribs are separated from each other by a shallow furrow, 

 which becomes wider between the first two or three upper 

 ribs, by the disappearance of the intermediate ribs. The lon- 

 gitudinal stria3 of growth are numerous, very fine, and slightly 

 apparent. The aperture is narrow, for it is much contracted 

 by two protuberances situated upon the two lower thirds of 

 the colurnella. The right lip is arched, flattened, widened 

 within, having a wide longitudinal ridge outside of it ; it has, 

 on the inside, the whole length, from sixteen to eighteen 

 ridges, or very strongly prominent teeth. The edge is un- 

 dulated and denticulated. The left lip is thin, diaphanous, 

 spreading upon the body of the shell, to which it adheres, 

 except towards the base, where it becomes free and thicker. 

 The columella is twisted, and presents a very deep emargina- 

 tion, above which is seen a wide, thick, furrowed tubercle, 

 which appears as if suspended over this hollow ; another 

 tubercle projects near the base, separated from the first by 

 the cavity just spoken of ; it is furnished with wrinkles and 

 numerous furrows of a brilliant white, which imperceptibly 

 diminish in size at the base, and above the emargination, 

 which is turned out like a gutter, and perfectly smooth. The 

 color of this shell is whitish, slightly blended with a dull 

 yellow. The interior is red. The epidermis is thin and 

 yellowish. 



Length 5 inches. Width 4 inches. 



Inhabits the South Sea, the Pacific Ocean, the coast of 

 Mexico, at Acapulco. 



This shell, which becomes often very large, and which is still 

 quite rare in collections, is that which Valenciennes has de- 

 scribed under the name of MALEA latilabris (Recueil cF Obser- 

 vations de Zoologie, Humb. et Bonpl. p. 325). It is exceedingly 

 remarkable for the development of the right lip, which is wide 

 and provided with strong teeth throughout its whole length. 

 The form and the situation of the two tubercles which pro- 

 ject from the columella are also very singular, and concur to 



