106 LlTTORINlDiE. 



R. RUFiLADuuM, (Leacli) Aider. 



Small, solid, with numerous rows of punctures on the dorsal 

 surface of the body-whorl, whose ventral surface, along with the 

 penult turn is, for the most part, densely and coarsely ribbed : 

 peristome tinged with purple : outer lip margined by a broad 

 white varix. 



Plate LXXVII. %. 8, 9. 



Rissoa hyalina, Desmar. Bullet. Soc. Philomat. Paris, 1814, p. 8 (copied 

 Desh. Lam. Aiiim. s. Vert. vol. viii. p. 473), pi. 1, f. C, 

 young ? 

 „ imnclala, Potiez and Mich. Galerie Douai, Moll. vol. i. p. 274, pi. 20, 



f. 3, 4 ? 

 „ lilacina, Recluz, Revue Zoolog. Cuvier. 1843, p. 6, probably. 

 Cingula rufilahris, of Leach ? Bean, Brit. Marine Conch, p. xl. fig. 4G. 

 Rissoa rufilccbrum. Alder, Annals Nat. Hist. vol. xiii. p. 325, pi. 8, f. 10, 11 

 (as Ahania rufilabrum of Leach, MSS.). 



In the uncertainty which prevails as to whether either 

 of the first two cited species may have been constituted from 

 the immature state of this very distinct shell, we have pre- 

 ferred to retain the appellation by which the species is 

 generally known to British collectors, although the descrip- 

 tion of lilacina agrees so far well, that we were almost 

 tempted to substitute that name from its prior publication. 

 The synonymy of the Rissoa has proved very laborious, for 

 we have had to compare each of our British species with 

 between one and two hundred exotic ones, very many of 

 which (those of Cantraine and Moller, for example) are so 

 meagrely characterised, that we have not ventured to refer 

 to them, even where they approach the features of our 

 indigenous shells. Moreover, a conversance with foreign 

 collections has taught us, that the range of variation for 

 each species is far wider than is generally imagined, so 

 much so indeed, that we can scarcely determine the limits 



