20 



BuLiMUS MiRABiLis. SlicU ratlicr long and conic, with two- 

 thirds of each whorl enormously inflated, gradually more abruptly 

 with the progress of growth, so as to give to the shell the form of a 

 screw ; subtransparent, whitish ; with numerous miscroscopic spiral 

 strios, and very distant transverse erect lamellar ribs, which have 

 smooth rounded edges, and are most elevated at the summit of the 

 convexity of the whorls, and diminish much over the anterior extrem- 

 ity of the shell ; spire with rather convex outlines ; apex with the in- 

 flation proportionally much longer and the ribs but slightly elevated ; 

 whorls about seven, with an indistinct suture ; aperture modified 

 by the form of the last whorl at its termination, and by the remarka- 

 bly prominent and much twisted columella, nearly into the form of 

 the figure 8. 



Length .1 inch; breadth .0G2 inch. 



This most extraordinary of all the land shells which I have seen, 

 strikes the beholder with amazement, and its novelty renders descrip- 

 tion difficult. 



Helix patina may be a variety of H. acutissima, Lam., but it is 

 concave on both sides of the periphery, like H. soror, while La- 

 marck's shell is always convex below and usually also above the per- 

 iphery : the surface of H. patina is smooth throughout, except a slight 

 granulation near the end of the last whorl, and is rather irregularly 

 impressed with scattered lines, which are mostly perpendicular to the 

 striae of growth. 



Greatest breadth 2.2 inches ; least breadth 2 inches ; height 1 inch. 



Helix fluctuata resembles the preceding, but the surface is 

 more uniformly and regularly granulated even than in H. acutissima: 

 the outline of the last whorl is an oval considerably elongated ; on 

 tlie first half of this whorl, the shell is concave on both sides of the 

 periphery, which next rather suddenly becomes obtuse : the lower 

 side is very convex through the central region, and the upper surface 

 is obliquely waved or wrinkled. 



Greatest breadth 2.2 inches ; least breadth 1.7 inch ; height 1 

 inch.* 



Helix cara. Shell convex above, more convex beneath, with a 



*The largest Helix acutissima ^vl^ich I have seen is 2.."} bj 2.03 inches, and the 

 smallest mature individual is 1.1 bj' .95 inch. 



