72 EOCENE MOLLUSCA. 



Spec. Char. U. testa tenui, ovato-oblongd, obliqud, gibbosd, laevigata, subcarinatd, 

 valde incequilalerali, siphoni-regione latiore ; margine ventrali incurvatd, margine dorsali 

 convexmsadd ; striis accretionis notatd. 



Shell thin, ovately oblong, oblique, gibbous, smooth or with visible lines of growth, 

 subcarinated ; very inequilateral, with siphon al region the broader ; ventral and dorsal 

 margins curved, but not parallel. 



Length, 2 inches. 



Localities. Highgate {Weiherell), Newnham ? {Presticich). 



Mr. Sowerby, in ' Min. Conch.' above referred to, considers this as doubtfully identical 

 with the Paris basin shell, but thinks it probable it may be the same as M. modiolus of 

 Brocchi. 



In the first part of ' Coq. foss. des Env. de Par., t. i, p. 250, M. Deshayes has 

 rejected the British fossil from among his synonyms on account of its dissemblance, but 

 he has admitted it with a mark of doubt in his second part (Descr. des An. s. Vert., t. 2, 

 p. 25). I am unable to throw any light upon this disputed point, and have therefore left 

 it with the name originally given by Mr. Sowerby, but I fully agree with the French author 

 that it cannot be united to M. modiolus, Linn. M. Deshayes says his shell very closely 

 resembles an oriental species which Mr. Hanley has named Modiola Metcalfei, except that 

 in the recent shell the dorsal edge is more elongated ; but it is not so in our fossil, which 

 bears a very strong resemblance to the Indian shell, and I think it probable the three may 

 be united under one name. There is in the recent British species and Crag fossil, 

 M. modiolus, considerable variation, more so than is exhibited between the Eocene fossil 

 and the Indian species. 



17. Modiola sulcata, Lamarck. Tab. XIII, fig. 11. 



Modiola sulcata. Lam. Ann. du Mus., t. vi, p. 222 ; and t. ix, pi. 17, fig. il a, b. 



_ _ i) es k. Coq. foss. des Env. de Par., t. i, p. 258, t. 39, tigs. 9, 10. 



— — Morris. Catal. Brit. Foss., p. 212, 1854. 



— — Desk. An. sans Vert, du Bassin de Par., t. ii, p. 15, 1860. 

 Mytilus sllcatus. Desk. Ency. Meth. Vers., t. iii, p. 566, No. 26, 1830. 



Spec. Char. " Testa elongatd, spathulatd, obliqud, depressd, antice posticeque longi- 

 ludinaliter sulcata, in medio lavigatd ; umbonibus minimis; margine antico breviss/mo, 

 crenulato." 



Shell elongate, spathulate, oblique, depressed, both sides striated or radiated ; central 

 portion smooth ; umbones small ; anterior margin (pedal region) very short, crenulated. 



Length, f ths of an inch. 



Localities. Barton {Edwards). 



France, Grignon, Parnes (Deshayes). 



