464 AURicuLiDj;. 



marginal line revolving near it ; the lowest whorl much larger than 

 all the others together ; aperture ovate, broadest below ; outer lip thin 

 and sharp, reflexed and white, joining the preceding whorl 

 ^'^A ^-y ^ ^^^y ^^^^^^ angle ; on the inner lip the adult shell has 

 O three white folds or teeth ; the lower one formed by the 

 ^ turning of the lip within the ai^erture ; the second tooth-like 

 sous, and nearly transverse, thin and prominent, a little below the 

 middle of the inner margin ; and a third, minute one, a little 

 above ; the lower portion of the left margin expands a little, and 

 conceals a very minute umbilicus ; two or three teeth are also some- 

 times found within the outer lip. Length, three tenths of an inch ; 

 breadth, five fortieths of an inch ; divergence, thirty-five degrees. 



Found in the crevices of decaying wooden wharves, about and 

 below high-water mark, in shaded situations. From Nova Scotia to 

 Rhode Island. It is an European species, inhabiting England, 

 France, Spain, <fcc. 



Animal very light drab color, head and tentacula darker and 

 wrinkled ; tentacula about one tenth of an inch in length, globose 

 at tip, the eyes kidney-shaped, and seated on a slight enlargement 

 at the inner base of the tentacula ; foot about half the length and 

 width of the shell, rounded behind, two-lobed in front, and trans- 

 versely divided at the anterior third. Respiratory orifice far back, 

 on the right side. 



This little shell is very readily distinguished from any other found 

 on our coast, and seems to be another of the connecting links be- 

 tween the land and water shells, or rather between those which 

 breathe air and those which breathe water. It has, accordingly, 

 been frequently transferred from one genus to another, according 

 to the conjectures of different writers. Guilding placed it rather 

 doubtfully, after a series of experiments as to the nature of its res- 

 piration. Its habits certainly associate it with the Mclampus biden- 

 tatus. It is widely distributed over the seas, and is doubtless con- 

 veyed to great distances on floating pieces of decaying timber. 



It varies much in its characters according to its age. Its color 

 varies from light horn color to deep violet, and sometimes it be- 

 comes opaque-white. There is usually a single revolving line of 

 rigid hairs just before the suture. When young, it is proportionally 

 broader, and the lower whorl proportionally longer, has but two 

 teeth, and the margin of the lip is not rcfiexed. A third, and some- 

 times a fourth, tooth appears at maturity, and also some teeth or 

 tubercles within the right lip. This is, indeed, made a part of its 



