RISSOA. 137 



and LitorineUa (Braun), have been severally applied to 

 this group, more on surmise of its peculiarities than through 

 precise distinguishing of its characters. 



We owe our opportunity of examining the animal 

 to Mr. Pickering, a gentleman well versed in the terres- 

 trial and fluviatile Mollusca of Britain. It is found, but 

 is rare, in the brackish waters of the marshes near Green- 

 wich. Draparnaud described it as a French species. 



An obscure species, whose described characters are not so very unlike those 

 of anatina, is only known to us as the 



Turbo subumbilicatus, Mont. Test. Brit. vol. ii. p. 31G. — Maton and Rack. 

 Trans. Linn. Soc. vol. viii. p. 1G5. — Rack. Dorset 

 Catalog, p. 50. — Turt. Conch. Diction, p. 204. — Dii.lm'. 

 Recent Shells, vol. ii. p. 841. 



Cingula si(bumhilicata, Brit. Marine Conch, p. 181. 



Rissoa „ Brown, Illust. Conch. G. B. p. 12. 



All the authors cited above have manifestly drawn their descriptions of tliis 

 very doubtful species from the pages of Montagu. Rackett and Brown liavc, in 

 addition, both figured shells which they supposed to be identical with it. The 

 delineation in the "Dorset Catalogue" is so small and rudely executed (pi. 18, 

 f. 12, b), that we cannot determine what species was intended by it ; possibly 

 ulv(B, var. stagnalis. Brown's figure (111. Conch. G. B. pi. 9, f. 44), thougli larger, 

 is, like nearly all his other magnified representations, very inadequate ; it bears 

 some resemblance to an abbreviated form of ventrosa. 



The C'mgnla subumbUicata of Fleming is quite a different thing, and evidently 

 not copied from Montagu ; for he remarks that it is common about the roots of 

 Fuci, and declares it to be greenish grey, with from five to seven whorls, instead 

 of yellowish white, with but four or five volutions. The 7?. subumUUcata of 

 Berkeley, again, is not represented in the engraving as having the few and tumid 

 whorls of Montagu's shell, but as composed of several flattish or plano-convex 

 volutions. 



" A smooth, subglossy, conic, yellowish-white shell ; volutions four or five, vcrj- 

 tumid, the first occupying above half the shell : apex rather obtuse : aperture 

 oval : outer lip even : inner lip a little reflexed, forming a sulcus or subumbilicus. 

 Length one-eighth of an inch ; breadth one-half its length." Montagu further adds, 

 that it difl^ers from uIvcb in being smaller, more ventricose, and more umbilicated ; 

 by its aperture, and the greater tumidity of its volutions ; from verilrosa, by its 

 superior size, its greater breadth at the base, and its exactly ovate aperture, 

 which is not contracted into an acute angle posteriorly as in the above-mentioned 

 species. Mr. Bryer, who has caused the introduction of so many exotic shells 

 into our Fauna, is stated to have found it on the shore at Weymouth. 



VOL. III. T 



