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Show 464 MR. HARPER PEASE ON POLYNESIAN LAND-SHELLS. [May 2, perist. simplex, continuum, ad anfr. penultimum adnatum aut dis-junctum, interdum vix porrectum; anfr. ultimus scepe ad peripheriam subangulatus. Animal operculumque gen. Omphalotropis, Pfr., persimilis. The shell of this genus is elongate, sometimes cylindrical, rarely ovate, imperforate, in the species of ovate form narrowly perforate; aperture ovate, occasionally circular; peristome continuous, sometimes disconnected from the penultimate whorl and very slightly porrected. The last whorl is frequently obtusely angulate on its periphery, of one colour, usually pale yellow or reddish. The species furthest removed from the type of Omphalotropis, viz. A. viridescens,Vse., and ventricosa, Hombr., can scarcely be distinguished from genus Blanfordia, A. Ad.; those approaching the nearest, vescoi, Dohrn, &c, are of small size, narrowly perforate, abbreviately ovate, but wanting the angulation around the umbilicus. In the following catalogue they are separated from the typical forms. Genus C Y C L O M O R P H A , Pse. Typus, Cyclostoma flavum, Brod. P. Z. S. 1832, p. 59. Testa turbinata, subglobosa, solida, lavigata aut spiraliter striata, perforata; apertura fere circularis; peristoma simplex, subin-crassatum, callo tenui continuum. Operculum ei gen. Omphalotropis, Pfr. similis. The shell of the above genus differs widely from any of the genera of the subfamily Realiea, Pfr. From its similarity to those of the genus Ostodes, Gld., the species have been heretofore included bv Drs. Pfeiffer and Gould in that genus. Having received a number of specimens collected alive with the operculum, I discover it to be certainly related to the above subfamily and to Cyclostomince; while the genus Ostodes belongs to the subfamily Cyclophorince. I also notice that Ostodes cenomphalus, Phil., arranged by Dr. Pfeiffer next to C. flavum, Brod., and included by Dr. Gould in his genus Ostodes, is described as being carinately angulate around the umbilicus, one of the peculiar characters of the genus Omphalotropis. It should be connected with the above genus, serving to confirm its position in the subfamily Realiea, Pfr. Its locality is unknown; the other species inhabit the extreme easterly portion of Polynesia. Having had an opportunity of examining the operculum of three species of the genus Ostodes, I extend the description given by Dr. Gould as follows :- Genus O S T O D E S , Gld. Ostodes, Proc. Bost. Soc. vol. viii. 1861, p. 283. Operculum tenue, membranaceum, circulare, margine tenuissimo, lacerato ; extus fornicato-convexum, nitidum; multispirale; anfr. 8-10, lente accrescentes, fere eeepiales ; sutura linearis, nucleo ; apex vix elcvatus, papi/latus ; subtus regulariter concava. |
