RISSOA. / 



The Twho striatulus of Linne appears to have been 

 Parthenia varicosa of Yovhe^^ Chemnitzia pallida ^ Phi- 

 lippi. Da Costa described and figured the present species 

 as T. carinatus ; and I would have adopted that original 

 and expressive name, were it not for the consideration 

 that, no subsequent author having done so, I have no 

 msh to be singular, or to make any unnecessary change 

 in the nomenclature. Tm-ton called this shell T. monilis, 

 Michaud R. cochlea, Philippi R. labiata, and Leach Per- 

 sephona brevis. 



2. E. lac'tea-^, Michaud. 



R. lactea, Mich. Descr. esp. Riss. p. 9, f. 11, 12; F. & H. iii. p. 76, pi. 

 Ixxix. f. 3, 4. 



Shell oval, compressed towards the mouth, rather thin, 

 semitransparent and somewhat glossy when h\'ing, opaque and 

 lustreless when dead : sculpture, shght and gently curved lon- 

 gitudinal ribs, which are seldom continued below the periphery 

 and are crowded near the outer lip ; there are about 20 on the 

 last and 10 on the penultimate whorl ; these ribs are crossed 

 by fine spiral striae, 15 of which are on the last and 9 on the 

 penultimate whorl ; the ribs are more prominent than the 

 striae, the points of intersection never being nodulous ; there 

 is sometimes, but rarely, a slight labial rib ; the first two 

 whorls are perfectly smooth : colour whitish, with a faint tinge 

 of yeUow, in dead shells milk-white : spire abnq^tly pointed : 

 u'liorls D-6, moderately convex, compressed towards the front ; 

 the last composes nearly three-foiu-ths of the shell, and the 

 fii'st two are minute : suture slight but distinct : mouth oval, 

 produced and angulated above, spread out below, not expanded 

 outwards; inside plain: outer lip rather thick : inner lip broad, 

 reflected over the pillar, and united with the outer Up at the 

 upper corner of the mouth, where there is a considerable 

 thickening: operculum pale horncolour, with a short spire, 

 and not conspicuously striated. L. 0-233. B. 0-15. 



Habitat : Under stones at extreme low water of 

 spring tides, and thi'own upon the beach : St. Aubin^s 

 * Milk-white. 



