22 Binney on Terrestrial Mollusks. 



HELIX CULTELLATA Thomson. 

 Plate LXX\a. Figure 6. 



Testa orblculato-depressa, nitens, carinata, cornoo-rufescens, ad peri- 

 pheriam et ad suturas albo-zonata ; anfr. 6^ convexiusculi, striis minutis 

 incrementalibus at lineis microscopicis spiralibus decussati ; sutura im- 

 pressa, apertura oblicjue lunaris ; pcrist. simplex, acutum. ad columcllam 

 vix reflexiusf'uliim ; subtus Ifevigata. albida, infra earinam late rufo-corneo- 

 zoiiata ; umbilicus perspectivus, anfr. omnes ad apiccm monstrans. 



SYNONYMS AND REFERENCES. 



Btlix cufteZfaia Thomson, in Proc. Phila. Acad. Nat. Sc. ix. p. 1S5, Oct. 1857; 

 Notes, p. 5. 



DESCRIPTION. 



Animal twice the length of the diameter of the shell; 

 color reddish. 



Shell orbicular, depressed, carinated, shining, reddish 

 horn color, with a broad revolving band of white at the 

 periphery and sutures ; whorls 6|, rather convex, decussated 

 by minute lines of growth and microscopic revolving lines ; 

 below these lines are obsolete, the surface is shining, whit- 

 ish, with a broad reddish horn-colored band below the 

 carina ; suture impressed ; aperture oblique, lunate ; peris- 

 tome acute, not thickened and scarcely reflected at the 

 umbilicus, which is broadly expanded, and shows all the 

 volutions to the apex. 



Greater diameter, 35 ; lesser, 19 ; height, 13 millimetres. 



Geographical Distribution. Found plentifully in Contra 

 Costa Co., California, by Mr. J. H. Thomson, of New 

 Bedford, Mass. 



Remarks. Mr. J. H. Thomson, of New Bedford, Mass., 

 proposes this name for a shell found by him living in con- 

 siderable quantities. The circumstances in which it was 

 discovered are very unfavorable to the supposition of its 

 having been brought from abroad. The chances of a 

 Dalmatian shell having been introduced into California, 



