542 TROCHID^. 



Trochis subcarinatus, Recluz, Revue Zoolog. Cuvier. 18413, p. 108. — Hani. 



Brit. Marine Conch, p. xxxix. (altered from Turbo s. 



p. 170.)— Brown, 111. Conch. G. B. p. 19, pi. 11. 



f. 30, 31. 

 Natica ? subcarinata, Philippi, Moll. Sicil. vol. ii. p. 141, pi. 24, f. 13. 



It is to Sclssurella and the smaller Delphinula, not to 

 Trochus, that we must look for a sculpture analogous to 

 the exquisite carving which distinguishes this beautiful 

 shell from our other British testacea. 



The shell is entirely white, strong for its size, almost 

 opaque, or only a little hyaline, and of a rather oblique 

 and very depressed turbiniform contour. It is composed 

 of from three and a half to four volutions, which increase 

 rather rapidly in size, are flattened or concave above, and 

 are moderately rounded below ; the apex is scarcely at all 

 elevated. Four strong nearly equidistant spiral ribs adorn 

 the exterior of the body whorl, which, moreover, has a 

 slight marginal thickening below the well-marked suture 

 likewise. The two stronger of the belts are seated upon 

 the superior surface, and the upper is continued along 

 the higher portion of the smaller whorls. They are all 

 more or less nodosely crenated, in the fresher exam- 

 ples, by somewhat flexuously arcuated lamellar stria?, 

 that traverse the exterior in a somewhat obliquely 

 longitudinal direction. These latter are numerous, but 

 not crowded, that is to say, are not broader than their 

 interstices ; are coarse upon the upper disk, and delicate 

 upon the lower one, where they encircle the profound um- 

 bilicus. The base is more or less flattened, and the per- 

 foration is preceded toward the inner lip of the aperture by 

 a broad shelving space that increases its apparent magni- 

 tude. The aperture is not distinctly nacreous, and is quite 

 smooth ; when viewed from below it appears of a rounded 

 ovate figure ; the inner lip, which recedes greatly, is a little 



