RHYNCHONELLA. 73 



It is probable that, when alive, B. spinosa was more or less coloured with red ; at least, 

 we have seen many specimens, in which the spines had preserved that colour; this is also 

 the opinion of M. Deslongchamps, and it is alluded to by V. Buch in his description of the 

 species. B. spinosa is found in the inferior Oolite of many localities, as at Dundry, near 

 Bath, Minchinhampton, Cheltenham, &c, where many fine specimens, with the spines 

 preserved, have been discovered by Dr. Wright, and Messrs. Lycett, Walton, and 

 others, a fine series of all the varieties may be seen in the Museum of the Bristol 

 Institution. 



In France it abounds; in Normandy, at Falaise, Moustiers, Port-en-Bessin, Sturfenberg, 

 and many other German localities. 



Fig. 15. A specimen, with its spines. 

 „ 16". A variety, with few plaits, from Dundry. 



„ 17, 18. Enlarged representations of the beak, foramen, and deltidium. 

 ., 19. Is drawn from a specimen in Dr. Wright's collection. 



„ 20. From a young specimen, showing the dichotomizing and intercalation of 

 some of the plaits. 



QQ. Rhynchonella senticosa, V. Buch, Sp. Plate XV, fig. 21. 



Terebratula senticosa, Von Buch, 1834. Uber Terebrateln ; and 1838, Mem. de la 



Soc. Geol. de France, vol. iii, p. 162, (non Ter. senticosa, 

 Schloth., which is a synonym of Spinosus of the same 

 author.) 



Biagnosis. Shell transversely oval, depressed, wider than long ; valves convex ; beak 

 small, acute, not much produced or recurved ; foramen nearly surrounded by the deltidial 

 plates ; a small portion only being completed by the umbo ; marginal line nearly straight, 

 slightly curved in front, but not producing any distinct mesial fold or sinus ; valves orna- 

 mented by a vast number of minute longitudinal ridges, on which are implanted a vast 

 number of small tubular spines covering the whole surface ; from twenty to twenty-four 

 occupying the space of a square line; lines of growth strongly marked. Length 11, 

 width 13, depth 7 lines. 



Obs. The first mention of the term senticosa, is by Schlotheim, 1 who refers to Knorr's 

 figure, 2 which, as we have already remarked elsewhere, was the type of B. spinosus, so 

 named by Schlotheim in 1813, 3 T. senticosa of that author is therefore only a synonym. At 



so much incurved, as to lie close on the umbo, and therefore showing no tubular foramen, such as 

 Rh. tetraedra, &c, and others, such as R. concinna, wbere the foramen is not tubular, nor even entirely 

 surrounded by the deltidium, a portion being completed by the umbo. 



1 Die Petrifactendunde, 1820, p. 268, No. 30. 



2 Knorr Lapides diluvii, 1755, pi. B. W., fig. 4. 



3 Scblotheim Beitrage zur Natur. Vers., in Dr. Leonhard's Min. Tasch., vol. vii. 



