lo8 MR. G. NEVILL ON THE [Feb. I 7, 



" Acme^^ plus minusve existit. Species typica Renea bour- 

 guignatiana, sp. nov. 



This is a very curious little group, evidently closely allied to 

 Acme, from which it can be at once distinguished by the deep 

 pleurotomoid sinus, which is visible for some distance along the 

 suture, imparting to the outer lip, when examined from the side, an 

 excessively convex appearance (as it projects sharply forward), also 

 by the entire absence of any external callous rib, such as always 

 exists, more or less developed, in Acme. The shell is imperforate, 

 of comparatively thick and shining texture, with much-produced 

 cylindrical whorls and contracted aperture, deeply notched at tiie 

 suture, with its margins thickened within ; the columella is nearly 

 perpendicular, slightly twisted above, and superficially presents an 

 appearance of a channel-like indentation. The sinus itself is as 

 deep as in Paladilhia pleurotoma, Bourguignat, but has not the 

 same impressed " Pleurotomaria-Wke " mark along the suture, 

 arising, 1 suppose, from the fact that the notch in Renea is only 

 formed, as in Fleurotoma, when the animal is full-grown. 



Monsieur Bourguignat has pointed out to me tliat this genus 

 presents some analogy to the West-Indian Chittya of Livesay, which 

 also belongs to this family. 



I have taken as my type of the genus the new species which 1 am 

 about to describe under the name of Renea bourguignatiana ; 

 another species is the very rare shell described as Acme mentoni by 

 Dupuy, Cat. Extram. Gall. Test. No. 4, 1849, and Hist. Moll. 

 pi. xvii. fig. 3, from " under bushes at Grasse." 



Renea bourguignatiana, n. sp. (Plate XIV. fig. 7.) 



Testa imperforatOy elongata, omnino cylindrica, sat solidula, nitens, 

 cornea, eleganter ac confertim costata ; spira regulariter pro- 

 ducta, apice Icevigato, perobtuso ; anfractus 1~, convexiusculi, 

 sutura profunda separati, supremi 2^ IcBvigati, aut sculplura 

 ob.ioleta, alterifere cequales, perlente ac regulariter crescentes, 

 anfract. ult. injerne distincte angulatus, superne prope suturam 

 in scissuram terminans, Iceviter sulcatulus, costis persinuatis, ad 

 basim evanidis ; apertura parva, verticalis, subquadrangularis, 

 ad basim angustata, svperne sinu profunda munita ; perist. intus 

 album, valde incrussatum, marginibus callo distinctojunctis, externa 

 quasi perconvexo ac wedio introrsum prominente ; columella su- 

 perne sinuata, subrecta, inferne acute angulata. 

 Long. 4, diam. 1 millim. 



This interesting form would appear to have been formerly fairly 

 abundant, though not nearly so much so as Acine foliniana, with 

 which it is always associated. We procured from deposits A, B, 

 and C about thirty or forty perfect specimens. The sculpture is very 

 remarkable; the two apical whorls are smooth and shining, the next 

 two slightly more convex than any of the others, their sculpture 

 is more or less subobsolete ; the next two are of equal size, slightly 

 convex, with almost vertical, distinct, and very close-pressed ribs, 

 the anlcpenultimate unc is a shade larger, fairly convex, and with 



