248 CEETACEOUS PELECYPODA 



already met with in triassic beds, and others occur in the Lias and Dogger, hut no 

 cretaceous species has yet been sufficiently ascertained. The genus had been 

 mistaken for Sphccra, under which name also most of the species appear to have 

 been described. 



8. Corhis, Cuv., 1817, (Gafrarium* Bolten, apud II. and A. Adams). Shell 

 oval, sub-equilateral, moderately tumid, usually with cancellated surface, hinge 

 with two cardinal, one anterior and one posterior lateral tooth, ligament long, 

 situated in a groove ; muscular impressions oval, the anterior generally somewhat 

 larger than the posterior. Type, C. fimhriala, Linn. 



The species of Corhis occur through all the mesozoic and tertiary strata, but 

 they are always rare shells ; equally so are the few recent species as yet known. 

 The triassic species like C. laticosta and 2)la7ia, described by Laube from St. Cassian 

 (Denksch. Akad., Wien, xxv, pt. ii, pp. 38 and 39, &c.,) may be compared with 

 Eri/clnella in the form of the hinge-teeth, 



9. CorUcella, Morr. and Lycett, 1853, (]\Ioll. Great. Ool., pt. ii, p. 91). 

 Shell ovately elongated, rather compressed, (tellinoid), sub-inequilateral, anteriorly 

 rounded, posteriorly a little less high and obliquely truncate at the end, hinge in 

 the left valve with one large anterior lamina-like, and another smaller bifid posterior 

 cardinal tooth ; in the right valve there is one small anterior and one large posterior 

 cardinal, and in each one posterior lateral. The type of the genus is Corhis 

 (CorhicellaJ Bathonica, M. and L., from oolitic beds near Minchinhampton. 

 Morris and Lycett state that the anterior lateral tooth is always wanting, but 

 though not well developed, it is certainly indicated by the internally strongly 

 thickened margin in such species as Corh. depressa, Desh., and still more in Corb. 

 Barrensis, Buv., (vide Loriol and Cottcau, Mon. Pal. and Geol., &c., Portlandien, 

 18G8, pi. 10, figs. 5 and 0). Tlie tellinoid compressed form of these shells and 

 their ornamentation, consisting merely of fine strioe of growth, shows a great simi- 

 larity to Mactromya, Ag., and readily distinguishes the genus from Corhis, but the 

 hinge, — judging from the variation of the teeth in the different species, — docs not 

 appear essentially to differ from that of this last named genus. 



10. Sportella, Desh., 1860, (Paris foss., 2nd edit., i, p. 593). Shell ovately 

 elongated, sub-equilateral, moderately compressed, with sub-parallel upper and 

 lower margins ; hinge in the left valve with two divei'giug unequal cardinal teeth, 

 the posterior being somewhat elongated, in the right with a large single median 

 and a small anterior cardinal tooth. Type, S. Caillati, Desh., from the eocene 

 beds of the Paris basin. 



I am not acquainted with any cretaceous or older species belonging to this 

 genus. Deshayes (I. cit., p. 594), says that some Jurassic and other species of 

 Sportella have been included by Agassiz in his 3Iaclroniya. It would have been 



* Bolten's name can bavdlj- be accepted for this genus, for it was actually proposed for a niixtum eomposituni 

 of the most varied genera of shells, and it is doubtful which should betaken as the type. M. v. Miihlfeld's name 

 Fimbria (1811) is pre-occupied by that of Bohadsch in 1761, and of the contemporaneous names Corhis and Idothea. 

 the former certainly deserves preference on account of its having been almost geucriilly accepted by conchologists, thougli 

 it was only lately given up by Deshayes and his followers for that of Fimbria which cannot be adopted. 



