OCR Text |
Show 1875.] MR. E. A. SMITH ON THE GENUS ALAUA. 537 peristoma continuum, ad margines superiorem labralemque aliquanto expansum. Diam. max. 20 mill. Diam. min. 15. Alt. 16. Hab. California. This very remarkable species was collected in California by Lord Walsingham ; and two specimens were presented to the British Museum by Mr. J. H. Ponsonby-a most enthusiastic conchologist, with whose name I feel much pleasure in associating the species. It has but one relation of any proximity, namely C. newberryi, Lea. From this it differs in being of a thinner and lighter build, in Carinifex ponsonbii. the more rapid increase of the whorls, and consequently in the proportionally much larger size of the last in comparison with the penultimate. C. newberryi has the upper surface of the whorls broadly flattened and then acutely keeled and angulated, whereas in the present species they are rather convex, lack the carination, and display but tbe faintest approach to an angulation, and this is situated near the upper and not the lower suture. Again, the mouth of the latter species ascends a little on the body-whorl; in the former it descends a trifle. Finally, Lea's shell is much more coarsely striated, and clothed with a strong yellowish-olive epidermis, whereas that which invests the present species is very thin and of a very pale olive tint. On each side of the rounded keel, encircling the umbilicus, there is a shallow depression. 3. Remarks on the Genus Alaba, with the Description of a new Species. By E D G A R A. S M I T H , F.Z.S. [Received June 23, 1875.] The genus Alaba was first characterized by Messrs. H. and A. Adams in the * Genera of Recent Mollusca,' p. 214, and there considered as a subgenus of Cerithiopsis. Subsequently it was raised to the rank of a separate genus and removed by A. Adams (see Annals & Mag. Nat. Hist. 1862, x. p. 294) to the subamily Litiopinse. Here the shells included in the group are described " anfractibus plicatis seu varicosis, vertice submammillato. Apertura ovata, labio seepe vix truncato." No mention is made of the nature of the operculum. |