76 LITTORINID^. 



ties in the south and west of Ireland (Thompson). It 

 ranges southwards to the Mediterranean. 



R. LACTEA, Michaud. 



Suboval, girt with elevated striae, that are decussated, except 

 in general upon the base of the body-whorl, by longitudinal 

 costellse or raised lines : spire short : suture simple ; throat 

 smooth. 



Plate LXXIX. fig. 3, 4. 



Twrbo canccUatus, Lam. Auim. s. Vert. (ed. Desh.) vol. ix. p. 218, fide Recluz, 



(irrecognizable). — Delkssert, Rec. Coq. Lam. pi. 37, f. 7. 

 Rissoa lactea, Michaud, Especes de Riss. p. 9, fig. 11, 12-. — Philippi, Moll. 

 Sicil. vol. i. p. 159 ; vol. ii. p. 129. — Potiez and Mich. Galerie 

 Douai, Moll. vol. i. p. 271. — Desh. Lam. Anim. s. Vert. vol. 

 viii. p. 4G6. 

 „ cancellata, Recluz, Rev. Zool. Cuvier. 1843, p. 8. 



Both this and the preceding species belong to the Littori- 

 niform types of the genus. The shell is tolerably strong, 

 but little if at all translucent, of a dull and uniform squalid 

 white (in fresh examples), and of an oval-acute contour. 

 The surface is elegantly sculptured by a peculiar decussa- 

 tion of raised spiral and perpendicular lines. The former 

 are the more apparent upon the body, where they appear as 

 rather crowded revolving costellffi, that become rather more 

 distant as they approach the anterior extremity : upon the 

 lesser turns tliey are mere lamellar arcuated strioe, and are 

 much more densely disposed (we counted six or seven on 

 the penult) than the longitudinal ones. The latter are 

 the more marked upon the spire, where they appear as 

 subpliciform lamellse ; they do not quite extend to the base 

 of the shell, are moderately distant from each other, but 

 ap[)roximate as they approach the outer lip. The suture 

 is rendered very distinct by the contrast between the 



