JURASSIC AND TRIASSIC BRACHIOPODA. 213 



inclusive. It is also probable that the shell which occurs in the Kelloway Rock of 

 Scarborough may represent the type of Schlotheim's species. 



217. Var. Smithii, Walker. Dav., Ool. Mon., p. 83, PI. XVII, figs. 15, 16; Sup., 



PI. XXVIII, figs. 1, 2, 3. 



Terebratula media, Smith (not T. media of Sowerby). Strata Identified by Organised 



Fossils, p. 32, plate facing 

 p. 32, fig. 9, 1816. 



Shell somewhat obscurely triangular, broadest anteriorly, and laterally rounded, 

 tapering posteriorly, wider than long. Dorsal valve most convex, and anteriorly divided 

 into three lobes, of which the central one forms a more or less elevated fold. When seen 

 in profile this valve is slightly convex at the umbo, from whence it is nearly straight to 

 within a short distance from the front, when it assumes a slightly upward curve ; it is 

 then abruptly bent downwards to meet the serrated frontal margin of the opposite valve. 

 The ventral valve is moderately deep and convex, the lateral portions being slightly 

 curved upwards near the margin. The sinus is wide and of moderate depth, beak small, 

 incurved, with a small circular foramen under its angular extremity, and margined 

 laterally by two narrow deltidial plates. The surface of each valve is ornamented with 

 about twenty-six small angular ribs, of which some six compose the fold and sinus ; the 

 ribs are also longitudinally indented along the middle for some distance from their 

 extremities. An average-sized specimen measured — 

 Length 7, width 8, depth 5 lines. 



Obs. — It is much to be regretted that Smith did not, in 1816, describe this shell with 

 a new name, instead of erroneously identifying it with Ter. media of Sowerby. Smith 

 states that he found the shell under description in the Fullers' Earth, near Bath, at 

 Charlton, Harethorn, Orchard Leigh. It is immensely abundant in the Fullers' Earth of 

 Great Britain, and wherever that formation occurs. It may be collected at Whatley near 

 Frome, Powerstock near Bridport, Burton, &c, and the specimens from all these and 

 other Fullers' Earth localities closely resemble each other. 



In PI. XVII, figs. 15, 16, will be found correct figures of this variety. It cannot, 

 however, be denied that specimens very similar to those found in the Fullers' Earth occur 

 higher in the series, and even as far up as the Lower Calcareous Grit. A specimen from the 

 Oxford Clay, in the Oxford Museum, is indistinguishable. This variety has been named 

 by Mr. Walker, after its first discoverer, the distinguished author of the work above 

 noted. 



