3S BRITISH CRETACEOUS BRACHIOPODA. 



shells, but it is only now and then that a large adult specimen is discovered. With age 

 the striae do not seem to augment much in width ; on the contrary, they are many times 

 larger in proportion in the young. 



T. striata is found in the Upper and Lower Chalk of Kent, Sussex, and Norfolk ; in 

 the Upper Green Sand near Warminster ; and in the Speeton Clay of Knapton, on the 

 Yorkshire Coast. At one time, I thought the Upper Green Sand specimens might belong 

 to another species, from being generally more elongated and rarely notched or indented in 

 front, this portion forming a regular outward curve ; but, having found, in the Lower or 

 Grey Chalk, near Dover, many examples quite identical with those from the Upper Green 

 Sand, I determined to give up that idea. I will not offer so decided an opinion relative to 

 the form found in the Speeton Clay, having been able to study only one specimen, lent 

 me by Mr. Bean, and which apparently presents some variations ; and, if constant, they 

 would entitle it to a separate appellation. It much resembles the figure which M. 

 D'Orbigny gives of Ter. Companiensis. This last-named shell is, however, always adult, 

 with much smaller dimensions. On the Continent, T. striata is met with in the same 

 stratigraphical range as in England, and is common to many localities. In Plate II, I 

 have endeavoured to illustrate the principal variations that I have observed in the British 

 specimens. 



Fig. 18. From the chalk of Norwich, in the collection of Mr. Fitch. 18". Enlarged 

 illustration. 



Fig. 19. Illustrates the interior and annular apophysary process, from a specimen in 

 my collection. 



Figs. 20, 21, 22, 23, 24. Young shells, from the Upper and Lower Chalk of Kent, 

 principally from the collection of Mr. Harris. 



Fig. 25. A specimen from the Gray Chalk, in the vicinity of Dover. 



Fig. 26. From the Speeton Clay of Yorkshire, in the collection of Mr. Bean. 



Figs. 27, 28. Two specimens from the Upper Green Sand near Warminster, from the 

 cabinet of Mr. Cunnington. 



14. Terebratulina gracilis, Schl. Sp. Plate II, figs. 13 — 17. 



Terebratulites gracilis, Schlotheim. 1813. Beitrage zur Naturgeschichte der Ver- 



steinerungen in Leonhard's Min. Tasch., vol. vii, p. 112, 

 tab. iii, fig. 3. 

 — — Schloth. Die Petrefactenkunde, p. 270, No. 35, 1820. 



Terebratula rigida, Sowerby. Min. Conch., vol. vi, p. 69, tab. 536, fig. 2, 1829. 



— gracilis, Schlotheim. Syst. Vers, der Petrefacten., 1832. 



— — VonBuch. 1834. Uber Terebrateln, 1838; and Mem. Soc. 



Geol. de France, vol. iii, 1st ser., p. 167, pi. xvi, fig. 1 1. 



— — Geinitz. Charak. der Schichten und Petrefac. der Sach. 



Kreidegebirges, 1839, p. 14, No. 4 ; and in 1840, pi. xvi, 

 fig. 13. 



