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Show 1867.] MESSRS. BAIRD AND ADAMS ON CHINESE SHELLS. 491 open umbilicus, and are of a large size ; but along with these are a number of specimens which differ in size and have the umbilicus closed. In almost every respect the smaller of these shells resemble the Nanina redfieldi of Pfeiffer ; but as there is one specimen with a closed umbilicus, nearly of the same size as the true N. ravida, and agreeing with it in every other point, it appears to be very difficult, with the exception of the closed umbilicus, to separate the two species from each other. There is also a small species of Helix in the collection, which appears to be an elevated variety of the H. ciliosa of Pfeiffer. 6th. Among the Unionidce are several specimens of the rather rare Unio nodosus of Wood, and one valve, exactly similar to the Barbata magnifica of Lea from Japan. Arconaia lanceolata (Triquetra lanceolata, Lea) and one or two species of Melania, more especially M. cancellata of Cantor, likewise occur in the collection. A single specimen of Meretrix (Cytherea, Lam.) zonaria (a rare shell), and several others might be enumerated. 7th. Another very interesting shell was brought by Dr. Lamprey, a single specimen of a species of Unio, belonging to a form which, till very lately, had only been observed in North America. This may be the Unio tientsinensis of Crosse and Debeaux ; but as it differs in some respects from the figure given by these authors, we are inclined to consider it distinct. UNIO (LAMPSILIS) SUBTORTUS, nob. (Pl. XXVI. figs. 1,1 a.) U. testa oblique ovata, valde ina;quilaterali, solida, ventricosa, concentrice rugoso-striata, ad marginem dorsalem oblique no-d- oso-plicata ; valvis subtortis ; umbonibus lateralibus, prominentibus, erosis, ad apices tuberculosis; margine dorsali convexo; margine ventrali ovato; latere antico declivi, convexo; latere postico elongato, oblique ovato, obscure angulato ; epidermide olivaceo-fusca, sericea; dentibus cardinalibus crassis, du-plicibus, subverticalibus, sulcatis, dente valvee sinistra; multum majore; dentibus lateralibus elongatis, subarcuatis, transverse sulcatis, in valva sinistra duplicibus; margarita albida. Long. 55, alt. 50, lat. 28 mill. Hab. Shanghai, North China (Dr. Lamprey). The nodose plications on the dorsal edge are elevated, but worn. They appear almost to have been originally blunt spines. The shell is longer than the species figured by Crosse, and not so tumid. UNIO (DYSNOMIA) LAMPREYANUS, nob. (Pl. XXVI. figs. 2, 2a.) U. testa subtriangulari, ineequilaterali, solida, compressa, concentrice late et valde plicata ; margine dorsali arcuato; margine ventrali arcuato; latere antico circulari; latere postico oblique ovato; umbonibus prominentibus, erosis; epidermide nitida, luteo-olivacea, fusco-viridi radiata ; dentibus cardinalibus crassis, verticalibus, duplicibus, sulcatis ; dentibus lateralibus |
