TEREBRATELLA. 27 



Terebratella pectinata, Smith. Identified by Organised Fossils, fig. 4, 1826 or 



1827. 



— pectita, Def ranee. Die. des Sc. Nat., vol. liii, p. 159, 1828. 



— — F.Buch. UberTer., 1834, and Meni.de la Soc. G£ol. de France, 



vol. in, p. 168, pi. xvi, fig. 12, 1838. 



— — Deshayes. Nouv. Ed. de Lamarck, vol. vii, p. 343, 1836. 



— — ? Hisinger. Leth. Succ, p. 79, pi. xxii, fig. 13, 1837. 



— — Rcemer. Des Vers. Nordd. Kreid, 1840. 



— — Morris. Catalogue, 1843. 



Terebratella pectita, D'Orb. Palseont. Franc. Ter. Cretacee, vol. iv, p. 120, pi. 517, 



figs. 16—20. 

 Terebratula pectita, Bronn. Index Palseont., p. 1244, 1848. (But not the fig. 3 



of Faujas, as stated by Professor Bronn.) 



— — Dav. Notes on an Examination of Lamarck's Brachiopoda. 



(Annals and Magazine of Natural History, vol. v, 1850.) 

 Terebratella pectita, If Orb. Prodrome, vol. ii, p. 173, 1850. 



Diagnosis. Shell more or less circular, or irregularly pentagonal, generally a little 

 longer than wide, sometimes the reverse ; valves seldom equally convex, the smaller one 

 being somewhat depressed, especially so longitudinally towards the centre, and proceeding 

 to the front ; no mesial fold or sinus ; hinge lines often very wide, and nearly straight ; 

 beak more or less prominent, slightly recurved, and diagonally truncated by a large and 

 entire foramen, partly surrounded by a deltideum in two pieces, which separates the 

 aperture more or less from the hinge margin ; beak ridges well defined, leaving between 

 them and the hinge margin a flat triangular more or less wide area. Surface of both valves 

 numerously and variably plicato-striated, augmenting rapidly in number from the 

 intercalation of plaits at different distances from the beak and umbo ; thus, in very young 

 specimens, I have counted only 26 plaits on each valve, while in some adult shells their 

 number at times exceeds 62, owing to intercalation at different distances ; concentric 

 lines of growth, often very strongly marked, intersect the longitudinal striae. In the 

 interior of smaller valve, the calcareous supports are doubly attached, first to the crural 

 base, secondly to the mesial longitudinal septum, after which the riband-shaped lamella, 

 again extending to a short distance, bend themselves back, forming the loop. Structure 

 punctuated. 



Dimensions variable; the largest specimen noticed in England measured length 11, 

 width 13, depth 7 lines, but in general not exceeding, length 10, width 9, depth 6 

 lines. 



Obs. All authors seem to have agreed in preserving Sowerby's name to this 

 elegant shell. It is very variable in shape ; the plaits in some specimens being delicate and 

 numerous, while the reverse is observable in others. The hinge line is also sometimes 

 as wide as the shell, but it does not in general exceed two thirds ; these variations 

 will be seen in the different illustrations we have given in Plate III, figs. 29 to 33, 

 all the specimens being from the Upper Green Sand of Horningham, Hill Deveril, near 



