170 CRETACEOUS LAMELLIBRANCHIA. 



? 1868. Tuetis majoe, A. Briart and F. L. Comet. Meulede Bracquegni.es (Mem. 



cour. et Ml' m. des Sav. etrangers, vol. 

 xxxiv),p. 83, pi. vii, figs. 14, 15. 

 1871. Fimbriella l^vigata, F. Stoliceka. Palseont. Iudica, Cret. Fauna S. 



India, vol. iii, p. 246. 

 1882. Thetis major, P. de Loriol. Gault de Cosne, p. 61, pi. viii, figs. 6 — 8. 

 ? 1874. W. Dames. Zeitscbr. d. deutscb. geol. Gesellscb., vol. xxvi, 



p. 766, pi. xxi, fig. 4. 

 1885. F. NiitUng. Die Fauna d. baltisch. Cenoman. (Palacont. 



Abliandl., vol. ii), p. 29, pi. v, fig. 6. 



Non 1845. SowERim var. ji major, E. Forbes. Quart. Journ. Geol. Soc, vol. i, 



p. 242. 



- 1846. major, A. d'Orbigny. Pal. Franc. Terr. Oct., vol. iii, p. 454, vol. 



ccclxxxvii, figs. 8 — 10. 

 l^vigata, d'Orbigny. Ibid., vol. iii, p. 452, pi. ccclxxxvii, figs. 1 — 3. 



- 1850. d'Orbigny. Prodr. de Pal., vol. ii, p. 118. 



major, d'Orbigny. Ibid., vol. ii, p. 160. 

 ?-- 1852. Sowerbyi, It. Kner. Denkscbr. d. k. Akad. Wissenscb. Wien, Matli.- 



nat. CI., vol. iii, p. 311, pi. xvi, fig. 21. 

 ? - - 1868. major, E. v. Eichivald. Letba3a Eossica, vol. ii, p. 708. 



Measurements : 



(1) (2) (3) (4) (5) (G) 



Length . 47 42 41 39 305 29-5 

 Height . 43 40 39 37 27 28 



(1—9) Blackdown. 



Affinities. — This species is closely allied to T. minor, with which it was united 

 by Romer under the name T. Sowerbii, but it possesses relatively higher and 

 narrower umbonus than T. minor. T. lasuigata is commonly of larger size than 

 T. minor, and as in the case of the latter, the large forms are more inequilateral 

 than the small forms. A rather small example was figured by Sowerby as Gorbula 

 laevigata, and was taken by Stoliczka as the type of a new genus Fimbriella , but it 

 proves to be, as was suggested by Pictet and Campiche, an example of T. major. 



The hinge can be seen in some specimens from Blackdown (Plate XXVT, figs. 

 10&, 14). It consists of two small conical or tubercular teeth just below the 

 umbo of each valve. In the right valve the teeth are placed one above the other, 

 but the dorsal tooth is slightly in front of the ventral and rather smaller than the 

 latter. In the left valve the teeth are side by side, nearly on the same level, 

 and the anterior tooth is rather larger than the posterior. Lateral teeth are 

 absent. The external ligament is short and prominent. 



Types. — The type of Gorbula laevigata, from Blackdown, and the types of 

 Thetis major, from Blackdown and Devizes, are in the British Museum. T. major 

 is the type of the genus Thetis, Sowerby. 



(7) 



22-5 



(8) 



22 



(9) 



13 mm 



21 



22 



13 „ 



