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. 



[EeceiTed May 26, 1879.] 

 (Plate XL.) 



At the request of Mr. Thomas Bland, of New York (who has 

 obligingly forwarded to me 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 de- 

 scriptions of such as appear to be new to science. 



Mr. Bland has also been good enough to furnish me 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 examiuation. 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 yabbi and Cryptostrakon gabbi. He 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 Tebennophoms, which he supposes to be T. cos- 

 taricensis of Morch. 



The species placed in my hands by Mr. Thos. Bland are as 

 follow, viz. : — 



1. Helix (Oxychona) zhorquinensis, 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 choco- 

 late 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 



