108 INVERTEBRATA. 



unequal, anterior ear trigonal, slightly truncated, convex in the 

 right and plane in the left valve; ornamented with the general 

 imbricating striae but devoid of rays. Posterior ear very small. 



Measurements. Length, 30mm.; breadth, 25 mm.; thickness, 

 12 mm.; apicial angle, 55". 



This shell is very generally known from Farringdon and Shank- 

 lin as Neithea Neocomiensis (d'Orb.). It is however not that 

 species, our shell being more elongated and more oblique, while the 

 characters of the intercostal grooves contrast clearly in both valves. 

 The ears also in d'Orbigny's species are subequal. 



I am by no means certain that this is not the original atavus 

 of Roemer. The description (Nordd. Ool. Sup., p. 29) tallies very 

 well with our shell, but the ears as figured are quite different and 

 agree with the French P. atavus. Yet it is our shell which occurs 

 'nicht selten' at Schoppenstedt. But unless the original figured 

 specimen can be discovered, the current ideas (d'Orbigny) are best 

 to be maintained. 



Besides the striking difference of the ears in our species and 

 P. atavus (d'Orb.), the broader character of the secondary ribs 

 serves also to distinguish it. 



Localities. Upware, Farringdon, Godalming (?). 

 iV. Europe. Schoppenstedt. 



HiNNiTES Leymerii, Deshayes. 



Hinnites Leymerii, Desh., 1842. Mem. Soc. Geol. Tr., tom. v. 

 p. 27, pi. 14, f. 1. 

 „ „ Pictet and Campiche, Pal. Suisse, Terr. 



Cret., St Croix, p. 224, pi. 175. 



A free valve from Brickhill. The internal cast shews well the 

 intermediate striae between the principal ribs. Where the shell is 

 preserved traces of the prominent scales on the ribs are seen. 



Locality. Brickhill. 



S. Europe. Perte du Rhone. 



