COlSrCHIFEEA. 449 



valve oblique or spiral, with, two hinge teeth, the anterior 



Fig. 246. Caprinella triangularis, Desm. U. Greensand, Eoclielle, ?-. 

 A, portion of the left valve, after D'Orbigny,* tlie shell-wall is removed bj" -weather- 

 ing, exposing the camerated interior. B, mould of five of the water-chambers. C, 

 mould of the body- chamber ; u, umbo of right valve ; s, of left valve ; t, dental groove ; 

 a, surface from which the posterior lobe has been detached. From, the originals in the 

 Brit. Mus., presented by S. P. Pratt, Esq. 



supported by a plate which divides the lunbonal cavity length- 

 wise. 

 In Q. triangularis th.e unibonal cavity of the spiral valve is 



Fig. 247. Straight valve. Fig. 248. Spiral valve. 



Transverse sections of C Boissii, L. Chalk, Lisbon (Mr. Sharpe). 



I, position of ligamental inflection ; t, teeth ; c, cartilage pits ; w, umbonal cavity. 



Fig. 248 is from a weathered specimen, which has lost the outer laj^er. The tubes of 



the shell-wall are filled with limestone containing small shells. 



partitioned off at regular intervals (Fig. 246, A) ; the length of 



3^ inches, and of the body- 



the water chambers is sometimes 



* In M, D'Orbigny's figure the smaller valve has been added from another speci- 

 men, and is turned towards the spire of the large valve, (Pal. Franc, pi. 542, fig. 

 1). In Mr. ir-ratt's specimens, and those collected by Mr. Sharpe in Portugal, the 

 umbo of tl;e smaller valve is turned away with a sigmoid flexure. (Q. J. G-eol. Soc 

 VI. pi. 18.) 



