196 Mr. H. B. Newton on Fossil JJolIusca d^c. 



liowevev, quite distinct, and they do not appear to have had 

 produced terminals to the cardinal region. 



Area cf. lacfea, Linnaiii?. (PI. VI. figs. 2, 3.) 



Jroa lactea, Linngsus, Syst. Naturae, 1758, ed. x. p. 694 ; Searles Wood, 

 Mon. Pal. Soc. (Crag xMoUusca) 1850, pi. x. tig. 2, p. 77. 



Fossularca lactea, Sacco, Moll. Terziarii Piemoute &c., 1898, vol. xxvi. 

 pi. iii. ijgs. 20-1^3, p. 19. 



Bemarh. — The two examples regarded as being closely 

 allied to the Mediterranean species lactea are of very similar 

 dimensions to that form, the length being about one and a 

 half times the height. The sculpture, which also agrees, 

 exhibits a series of fine and closely arranged costje crossed by 

 equidistant concentric growth-lines. The valves, however, 

 are rather compressed than otherwise, which would be the 

 chief reason for not regarding them as belonging to the true 

 lactea. The}' differ from Area ingeriensis, next described, 

 in their less angulate contour and more median umbones. 



Dimensums (largest example). — Length = 14, height = 

 9 mm. 



The Linnajan shell has been determined from the Pliocene 

 (Coralline and lied Orags) Leds of England, whilst Sacco 

 has recognized it under Fossularca of Cossmann, and considers 

 it as occurring in Italy in rocks ranging from Miocene 

 (Helvetian) to Pliocene (Astian) times. 



Area nigeriensis, s[). n. (PI. VI. figs. 4, 5.) 

 Description. — Shell small, inequilateral, oblong, length 

 ncnrly twice that of the height; anterior margin rounded, 

 posterior truncated, slightly excavated; stri» equal, nume- 

 rous and fine (about 60), crossed by concentric growth-lines; 

 valves depressed ventrally. 



Dimensions (largest specimen). — Lengtli = 17, height = 

 9 mm. 



Remarks. — This form is distinct from Area tetrogona of 

 Poll, found in the Mediterranean and in the Pliocene deposits 

 of Europe, by reason of its more equal striations and the less 

 elevated umbonal region. The radial costae ornamenting 

 the ]>osterior surface of A. tetragona are much stronger and 

 fewer than those of the present form ; both species, however, 

 are similar in possessing a horizontal hinge-line which is 

 parallel with the veiitral margin. 



Cardium cf. decorticatum, S. V. Wood. (PI. VI. figs. 6, 7.) 



Cardium decorticatum , S. V. Wood, Mon. Pal. Soc. (Crag Mollusca) 

 1853, pi. xiv. fig. 1 d, p. 159. 



Description. — Shell cordately ovate, slightly oblique, 



