444 PATELLIDiE. 



f Patella cerea, Moller, Index Moll. Greenland, p. 16 ( = candida, teste Moller). 

 9 „ 9 exigua, Forbks, in Thompson's Report, Brit. Assoc. Rep. for 1843, 

 p. 259. 



It is possible, from the small size of the very few 

 examples as yet taken, that this extremely rare Limpet 

 may not have reached its full stature ; and that the shape 

 and sculpture may not be precisely identical with that of 

 the species when fully developed. Hence our description 

 may not precisely correspond with some of the individuals 

 which may hereafter be discovered : hence, too, our sus- 

 picion that this shell may prove the immature state of the 

 Patella catca of Miiller. 



The individual now before us is conical, thin, semi- 

 transparent, a little oblique, somewhat laterally compressed, 

 and of a pure white, both within and without. The basal 

 margin has a rather elongated elliptical figure, is rounded 

 and nearly equally broad at both ends, and is convex at the 

 sides. The vertex is sharply pinched up, recurved, a little 

 spiral, and subcentral, or rather before the middle of the 

 shell ; the slope from it forwards is at first arcuated, 

 and then rather abrupt and but little convex ; the slope 

 posteriorwards is much more gradual, and, except imme- 

 diately below the spire, is almost straight. The external 

 surface, which is not polished, is densely covered with 

 very delicate elevated radiating lines, that are concen- 

 trically and closely decussated by equally fine imbricat- 

 ing lamellar ones, which produces a fimbriato-granular 

 appearance at the intersection of the tv.o. The inner 

 edge is nearly entire, or only subcrenulated by the external 

 sculpture. 



The length of the individual above-described, is only two 

 lines ; examples of cceca sent to us from Sweden, by our 

 eminent friend, Professor Lov^n, of Stockholm, of about 



