LAMELLIBRANCHIATA. 107 



outer ribs which are here nearly smooth, while in Sowerby's Upper 

 Greensand shell this part is well costated. 



Localities. Upware, Atherfield, Shanklin, Hythe. 



S. Europe. Perte du Rhone, Wassy, Spain. 



Range. Neocomian. 



Pecten (Neithea) atava (Roemer), d'Orbigny. 

 (Plate iv., fig. 6.) 



Janira atava, d'Orb., Terr. Cret. III. p. 627, pi. 442, f. 1 — 3. 

 „ „ Pictet and Campiche, St Croix, p. 237, pi. 180. 



I only know of one specimen from our neighbourhood and this 

 is in the cabinet of Mr J. F. Walker, M.A. 

 Locality. Upware. 



N. Europe. Hils formation of Shoppenstedt, Berklingen. 



8. Europe. Neocomian of France, Switzerland, Spain. 



Pecten (Neithea) ornithopus, sp. nov. 

 (Plate iv., fig. 5, a, b.) 



Shell subtrigonal, slightly oblique from the greater develop- 

 ment of the posterior side, very inequivalve, plano-convex or 

 concavo-convex, auriculate. It is ornamented with six prominent 

 radiating ribs, and subordinate stria?, the former being produced in 

 the form of claw-like processes. The whole surface is crossed with 

 delicate squamous growth-lines. 



Lower valve convex with prominent, narrow beak; primary 

 ribs (six) all well defined, the anterior one shortest and the fourth 

 longest ; they are angular, and covered with imbricating cross lines. 



Interradial grooves slightly narrower than the ribs, depressed, 

 furnished with a number of secondary ribs which are simple and 

 convex, separated by narrow grooves. Fifteen of these are seen in 

 the central furrow, counting those which extend half-way up the 

 sides of the adjacent ribs. 



Upper valve concave, plane, or even slightly convex; its primary 

 ribs similar to those of the lower valve, but slightly more rounded; 

 grooves deep, ornamented with radiating ribs and striae, which 

 are either broad and flat, or numerous and rounded. Ears very 



