76 HELICID^. 



Hdix chersifia. Say, Journ. Acad. Sc. Nat. Philadelph. vol. ii. p. 156. — Binney, 

 Boston Journ. Nat. Hist. vol. iii. p. 416, pi. 26, f. 3. — Gould, 

 Invert. Massach. p. 185, f. 105. 

 „ trocMlus, Fleming, Brit. Animals, p. 260. 

 „ Alortoni, Jeffreys, Trans. Lin. Soc. vol. xvi. p. 332, 507. 

 „ Mandralisci, BivoN (filius) in Giorn. lett. no. 198, f. 6. 

 Cornulusfalvus, Fitzinger, Syst. Verz. Erzh. Weichth. p. 94. 

 Polila fiilva. Held, Isis, 1837, p. 916. 

 Petasia troclnformis, Beck, Index Moll. Mus. Christ. Frid. p. 41. 



Minute, globose-turbinate, thin, pellucid, glossy, all but 

 perfectly smooth, not downy, of an uniform brownish or 

 yellowish horn-colour; whorls six, convex, very narrow, 

 well defined ; spire in the typical form elevated (in the 

 variety Mortoni it is depressed, both sides being there of 

 nearly equal convexity) ; apex rather obtuse. Base promi- 

 nent in surface, yet slightly flattened, with a minute in- 

 cipient umbilicus in the young, which is entirely concealed 

 by the reflection of the columella in the adult. Aperture 

 narrow, depressed lunar, ordinarily equal to half the basal 

 diameter ; peristome acute, simple, not reflected, except 

 upon the columellar lip. Diameter nearly the sixth of an 

 inch. Beneath a very powerful lens, the base of this tiny 

 shell exhibits most exquisitely fine spiral striolre. A 

 smaller and darker variety, in which this sculptm*e is 

 more than usually distinct, has been indicated by Mr. Al- 

 der. Generally speaking the more humid is the habitat, 

 the darker and more lustrous will the specimens prove. 



The animal is grey. 



It inhabits woods among moss, and is widely diftused.* 



" The Trochus terrestris of Pennant (Brit. Zool. ed. 4, vol. iv. p. 128, pi. 80, 

 f. 108, copied Brown, 111. Conch. G. B. pi. 14, f. 80, 81, the T. terrestris tertius of 

 Da Costa Brit. Conch, p. 36) appears to us to be a rude representation of this 

 species, but has been referred bj- some to the Carocollu vieyans of Lamarck, wliich 

 is a native of Southern Europe. 



