486 



We have obtained a fine series of the shells of the M. Hum- 

 phrey 'sianus, and believe it to be a smooth variety of this most 

 variable species. The Buccinum acuminatum of authors is 

 generally considered a flat-whorled variation of the "unda- 

 tus '" at present we accept that position, though with some 

 doubt, on account of the peculiar compressed character of the 

 volutions in the three examples we have examined. The 

 animal must decide the question. 



Sectio IV. Testa tumida, lavis, scepe spiraliter substriata. Canalis ob- 

 liquo-dorsali-bremssimus. Apertura ovalis. Columella dorso-fastiyiata. 

 Operculum corneum. 



PURPURA, Lamarck et Auct. 

 M. LAPILLUS, Linnaeus. 



Buccinum lapillus, Montagu. 



Purpura lapillus, Lamarck et Brit. Moll. hi. p. 380, pi. 102. f. 1, 2, 3 ; 

 (animal) pi. L.L. f. 4. 



Animal spiral, of a uniform pure white or pale yellow, 

 without the intermixture of other colours or markings, 

 except a single superficial fine longitudinal line of deeper hue, 

 which divides the under part of the foot into two portions. 

 The mantle is of very thin texture, lining the shell only to the 

 margin, except the part constituting the branchial fold, which 

 is occasionally carried, in marching, a little beyond the short 

 canal. The head is very small, slender and flat ; from this 

 spring the moderately long tentacula, which are tumid and 

 rounded from their bases, accompanied for two-thirds of their 

 length by offsets on which the eyes are placed externally, and 

 from thence running conically to not very pointed termina- 

 tions ; the mouth and its vertical fissure, from which a short 

 proboscis is very rarely seen protruded, are beneath. The foot 

 when at rest is nearly oval, but in action it is truncate and 

 auricled in front, somewhat attenuated in the middle, and has 

 a rounded termination, with, on its posterior upper surface, 

 an irregular oblong, red-brown, corneous, subunguiculated 

 operculum, having the lines of increment raised on the inner 

 surface. The buccal mass, as in all the Murices, lies within 



