﻿18 



ME. E. B. NEWTON ON A EOSSILIFEEOUS [vol. lxxii, 



Remarks. — The valves of this species are of abundant occur- 

 rence, while some of the adult examples measure from 80 to 85 

 millimetres in length and height. 



Distribution. — Vindobonian (Holland) ; Anversian to Scal- 

 disian (Belgium) ; Plaisancian and Astian (Italy) ; Boxstones, 

 Lenham Beds, and Coralline Crag to Post- Pliocene (Britain) ; 

 Recent (British and Boreal seas, non Mediterranean). 



IsOCAEDIA HUMANA (LhmJBUs). (PL II, fig. 13.) 



Cardium humanum Linnaeus, 'Systema Naturae ' 1758,-lOth ed. p. 682. 

 Ckama cor Linnaeus, ' Systema Naturae ' 1767, 12th ed. vol. i, pt. 2, p. 1137. 

 Isocardia cor Lamarck, ' Hist. Nat. Anim. sans Vert.' 1819, vol. vi, pt. 1, p. 31. 

 Isocardia humana Dall, Trans. Wagner Free Inst. Sci. Philadelphia (Tertiary 

 Fauna of Florida), 1900, vol. iii, pt. 5, p. 1064 



Distribution.— Tortonian (Italy, Holland); Plaisancian and 

 Astian (Italy) ; Diestian and Scaldisian (Belgium) ; Boxstones, 

 Lenham Beds, Coralline Crag, and derivative in Red Crag 

 (Britain) ; Recent (Mediterranean and British Seas). 



Family Dosiniidjs. 



SlNODIA TEETIABIA, sp. 110V. (PL II, figS. 14-16.) 



Description (Right valve). — Shell solid, insequilateral, sub- 

 orbicular, height in excess of length, well arched ; posterior region 

 deep, sloping, marginal curvature extensive ; dorso-anterior margin 

 oblique, straight, long ; ventral margin gradually ascending to 

 unite with the expanded and rounded edge of the lower anterior 

 side ; lunuloid region superficial, large, ovately-elongate, obscurely 

 circumscribed ; hinge area massive, deep, bearing two divergent, 

 thick, robust, cardinal teeth, also a third and smaller cardinal in 

 front, of more or less laminate appearance ; ligamental furrow wide, 

 long, and prominent ; pallial sinus triangulate, moderately wide at 

 the base, apex obtuse ; internal margin smooth ; surface covered with 

 well-marked, nearly equidistant, elevated growth-lines and numerous 

 finer concentric striae occupying the intervening spaces, the whole 

 crossed by obscure radial striations. 



Dimensions in millimetres. — Largest example, right valve. 

 Length = 50 ; height = 53 ; diameter = 16. 



Remarks. — The more striking features of this shell include the 

 anterior obliquity, the long and superficial lunuloid area, the nearly 

 equidistant growth-lines, and the extensive curvature of the pos- 

 terior margin. It appears to be allied to Cbemnitz's Venus excisa 

 rather than to the other forms referred to this genus, which are of 

 more distinctly trigonal contour. The shell is fairly common in 

 the North-Sea limestone, although it is difficult to obtain specimens 

 with perfect internal characters ; one example, however, does exhibit 

 a partial internal cast of a left valve, showing the presence of a 

 well-marked, obtusely-pointed, and triangulate pallial sinus. It is 

 proposed to name this shell Sinodia t ertiari a. 



