26 BRITISH CRETACEOUS BRACHIOPODA. 



British specimens, has given it the name of T. Jstieriana. It is necessary to remark 

 that many of the shells found in the Green Sand of Farringdon, whence our British 

 specimens were derived, are more or less rolled, and the valves disunited, the plaits being 

 slightly blunted 5 but during a later visit to that locality, I was able to obtain a few 

 examples quite as sharp and perfect as any of those from Mans, and corresponding 

 exactly with the description of T. Menardi, by Lamarck and M. D'Orbigny, and 

 which may be seen by comparing the two figures we have purposely given in Plate III 

 of the French and British specimens : fig. 42 is a French T. Menardi from Mans; fig. 38 

 a British specimen from Farringdon ; wherein these differ I am at a loss to perceive ; 

 the same number of plaits and mesial fold; the same character of area, foramen, and 

 general aspect ; they both possess the same wrinkled concentric lines of growth stated by 

 M. D'Orbigny to occur in T. Menardi, but not, according to him, in T. Jstieriana, in 

 which the number of costse are more numerous, of which I am convinced, from having 

 two typical specimens now before me, given to me by M. D'Orbigny himself, differing by 

 several characters from the Farringdon shell, being more oval, flatter, and possessed of a 

 greater number of smaller plaits. Our British specimens are, it is true, generally smaller 

 than the French ones, and rather thicker, but this no doubt arises from accidental and 

 local causes, which favoured more the development of the Mans specimens, an occurrence so 

 frequent among animals where local causes produce different races and varieties. Ter. 

 Menardi is stated to occur in Lower Green Sand, near Devizes, by Mr. Cunnington ;* on 

 the Continent it is abundant in beds of Mans (Sarthe), &c. 2 



Plate III, figs. 34, 35, 36, 37, 38, 39. Specimens from the Green Sand of Farringdon 3 



in my collection. 



„ fig. 42. A French specimen from the Mans. 



,, fig. 41. The smaller valve, showing the calcareous loop enlarged. 



„ fig, 40. The dental valve enlarged. 



9. Terebratella pectita, Soio. Sp. Plate III, figs. 29 — 33. 



Terebratula pectita, Sow. M. Con., vol. ii, p. 87, tab. 138, fig. 1, 1818. (Non 

 Pectita, Nilsson Petrefacta Succana, pi. iv, fig. 9, 1827.) 



— — Lamarck. An. sans Vert., vol. vi, p. 255, No. 46, 1819. 



— — Parkinson. An Introduction to Org. Rem., p. 227, 1822. 

 Terebratella pectita, Brongniart et Cuvier. Descr. Geol. des Env. de Paris, 



pi. ix, fig. 3, 1822. 



1 'Quart. Journ. of the Geol. Soc.,' vol. vi, p. 454, 1850. 



3 I believe Mr. Austen in error while stating, in the 'Quart. Journ. of the Geol. Soc.,' vol. vi, p. 477, 

 that T. truncata, Sow., is likewise found in the Upper Oolitic beds of Germany, whence at least I have 

 never seen any authentic specimen. 



3 The age of the Farringdon beds has not yet been satisfactorily settled. Mr. Austen and others state 

 them to be Lower Green Sand. 





