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Show 1879.] MR. G. F. ANGAS ON THE MOLLUSCA OF COSTA RICA. 475 3. On the Terrestrial Mollusca collected in Costa Rica by the late Dr. W . M. Gabb, with Descriptions of new Species. By GEORGE FRENCH ANGAS, C.M.Z.S., F.L.S., &c. [Received May 26, 1879.] (Plate XL.) At the request of Mr. Thomas Bland, of New York (who has obligingly forwarded to m e for examination the collection of land-shells made in Costa Rica by the late Dr. Gabb), I have undertaken, as far as practicable, to give in the following paper a list of the species obtained in that country by Dr. Gabb, together with descriptions of such as appear to be new to science. Mr. Bland has also been good enough to furnish m e with notes regarding the habitats of the various species, together with drawings of several of the animals, taken from nature by Dr. Gabb ; and these he has supplemented with some important remarks of his own. Although in some instances the number of specimens of a species sent is sufficient to form a good series for critical examination, in others there are but one or two examples available; therefore where there is any doubt in determining a species it will be marked with a ?. Through the liberality of Mr. Thomas Bland I have been enabled to place the type specimens (together with examples of most of the species sent), in the national collection in the British Museum. Previous to Dr. Gabb's decease, several of the Mollusca collected by him in Costa Rica, and preserved in spirits (together with his original drawings of the animals), were submitted by him to Mr. W . G. Binney for examination. In a paper just published in the ' Annals of the'New York Academy of Sciences ' (vol. i. pi. 11), Mr. Binney gives descriptions and figures of two new genera and species, viz. Velifera gabbi and Cryptostrakon gabbi. H e also figures the lingual dentition and the animals in motion. Furthermore, he figures the animals and the lingual dentition of Limax semitectus, Morch, and of a species of Tebennophorus, which he supposes to be T. costaricensis of Morch. The species placed in m y hands by Mr. Thos. Bland are as follow, viz.:- 1. HELIX (OXYCHONA) ZHORQTJINENSIS, n. sp. (Plate XL. fig. 1.) Shell scarcely rimate, conically trochiform, rather thin, under the lens very minutely transversely shagreened upon the lower whorls and on the base, pale yellowish green, with a single narrow chocolate band in the middle of the three or sometimes four lower whorls, and a still narrower band of the same colour next below the sutures; whorls 6, nearly 'flat, sharply keeled at the periphery ; sutures, the last three keeled and white; nucleolar whorls nearly smooth and shining, with a purplish-black line at the sutures, and spreading over |