100 Mr. R. Etlieridge on Carboniferous Lamellihranchiata. 



former horizon. Passing to the true Carboniferous Limestone, 

 E. unioniformis is met with in England at Bolland (Phillips), 

 Lowick (M'Coy), in Scotland at numerous localities, in 

 Belgium at Vise (De Koninck), in Russia at Kasatschy- 

 datschy &c. (De Verneuil and Eichwald). Proceeding still 

 upwards, Mr. Salter figured a specimen from the collection of 

 Dr. G. P. Bevan, obtained in the " Rosser-vein " ironstones, 

 between the Farewell Rock and millstone-grit, of Glan 

 Rhymney, South Wales, at the base of the Coal-measures *. 



Genus Leda, Schumacher. 

 Leda Traquairii^ sp. nov. PI. IV. fig. 4. 



8ip. char. Shell clavate, ventricose, short, and arcuated ; 

 anterior end large, rounded ; posterior end short, attenuated, 

 and obtusely pointed ; ventral margin arcuated, passing rapidly 

 up to the attenuated posterior end; umbones anterior more 

 than central ; hinge-area probably wide, and bounded by ob- 

 tusely rounded umbonal ridges, passing to the posterior end, 

 where they become lost; lunule ? hinge-teeth ? orna- 

 mented with regular, equal, flattened, concentric, rib-like striae, 

 uniting on the obtusely rounded posterior end in small bundles 

 to form broader and coarser fluctuations. 



Obs. The distinguishing characters of L. Traquairii are its 

 extremely short, clavate, and ventricose form, rapidly arcuated 

 base, and short attenuated end. These ^Joints, with its strongly 

 curved umbonal ridges and broad and flat concentric strige, 

 serve to distinguish the species from L. attenuata, Flem. The 

 general proportions of the two shells also vary considerably. 

 L. Traquairii appears to be intermediate between the latter 

 and Leda {Nucula) claviformisj Sow.f (non Phil.), from which 

 it may be distinguished by not possessing a truncated posterior 

 end. The posterior end is very short, as in Sowerby's species, 

 but is clearly rounded and not truncated. L. claviformis^ Sow., 

 to which the new species is closely allied in its clavate and 

 ventricose form, is said by Prof. Morris | and Capt. T. Brown § 

 to be a Lias form. Sowerby says, " in rounded masses of grey 

 limestone in the alluvial deposits so common in many parts 

 of Norfolk and Suffolk." Were it not for the definite state- 

 ment of these authors, I should feel much inclined to regard 

 N. claviformisj Sow., as a carboniferous shell. In his ' Car- 



* Mem. Geol. Surv. Iron Ores of Gt. Britain, pt. 3, p. 221. 



t Min. Conch, v. p. 119, t. 476. f. 2. 



X Cat. Brit. Foss. 1st ed. p. 94. 



^ Foss. Conch. 1849, p. 185. 



