116 MOLLUSCA FROM THE CRAG. 



in my Catalogue. The shell is very thin, and in the living state was no doubt nearly 

 transparent, it has a prominent umbo, sloping towards each extremity, and is rounded 

 there, while the ventral margin is quite straight, even inclining a little inwards in 

 some specimens, and is deep or tumid, particularly at the upper part; the hinge is 

 furnished with two teeth in each valve, diverging from the ligamental area, but do 

 not extend far towards the sides, and in the left valve immediately beneath the umbo, 

 and before the ligament, is a small cardinal tooth, but not one in the right valve ; in 

 perfect specimens the shell is beautifully glossy, and the exterior possesses a sort of 

 irregular concentric striae, which I imagine is not its original appearance, and that 

 probably it was ornamented in its recent state with more elaborate sculpture. 



3. LEPTON DEPRESSUM, Nyst. Tab. XI, fig. 6. 



CYCLAS? DEPRESSA. Nyst. Rech. Coq. Foss. d'Anv., p. 36, pi. 5, figs. 5, 6, 1836. 

 ERYCINA DEPRESSA. Nyst. Coq. Foss. de Belg., p. 88, pi. 4, fig. 5, , a, b, c, e, 1844. 



Spec. Char. Testa transversd, ovatd, in&quilaterali, depressd, tenui ; dente cardinali 

 unico, dentibm lateralibus obtusis. 



Shell transversely ovate, slightly inequilateral, depressed and thin ; hinge with one 

 cardinal, and two obtuse lateral teeth. 



Length, \ of an inch. 



Locality. Cor. Crag, Button. 



A single specimen of this shell in my Cabinet seems to correspond with what M. Nyst 

 considers, probably with better materials than I possess, to be a distinct species, and 

 the form certainly is different from that of any other already described ; and as I am 

 not imposing a new name, it will at least serve to call the attention of Collectors to 

 its existence for better examination. 



My specimen maybe thus more particularly described. One side is rather broader 

 or deeper than the other, the longer side being the more narrow, and slightly pointed, 

 the hinge teeth are very obtuse, perhaps not quite perfect, dorsal area truncate, with 

 a depressed umbo : lateral teeth not very distant, two ovate muscular impressions 

 rather deep, and a continuous line formed by the mantle. The exterior is somewhat 

 rough and eroded, but appears as if it once had a more regular ornament. M. Nyst 

 says of his shell : " Transversim subtilissime irregulariterque striata/' and that it is 

 in Belgium also a rare species. 



4. LEPTON NITIDUM, Turton. Tab. XI, fig. 7. 



LEPTON NITIDUM. Turt. Brit. Biv., p. 63, 1822. 

 Flem. Brit. An., p. 429, 1828. 

 8. Wood. Catalogue, 1840. 

 Thorpe. Brit. Mar. Conch., p. 49, 1844. 

 Macgill. Moll. Aberdeen, p. 278, 1843. 

 KELLIA NITIDA. Forb. and Hani. Hist. Brit. Moll., vol. ii, p. 92, pi. 36, figs. 3, 4, 1849. 



