20 THE INDIGENOUS FAUNA. 



species is undistinguishable in form from the Oxford ian Gryphea 

 dilatata; another shell (a form of 0. Walkeri) has long been labelled 

 Ostrea deltoidea in the Woodwardian Museum, and it is indeed 

 precisely like it ; and, again, the little Exogyra Tomhechiana (called 

 E. nana in the earlier lists of Mr Walker) seems to pass into the Ex- 

 ogyra nana of the Kimmeridge clay. The Brickhill oysters are some- 

 what different, 0. macroptera being there represented by 0. carinata. 

 It is not inopportune to point out the close resemblance of this 

 latter species also to the Ostrea gregaria of the upper Jurassic 

 rocks. 



The special development of the Arcadce at Upware is also 

 noteworthy, and particularly the occurrence of several species of 

 the uncommon genus Fectunculus. 



The Opis Neocomiensis and Cyprina Sedgwickii are conspicuous 

 and beautiful fossils at Upware, and the isolated appearance here 

 of several species of such a peculiar group of Cypricardia {G. striata, 

 C. arcadiformis, and C. squamosa Kpng.) is very remarkable; the 

 more so because one of them is identical with a species described by 

 Prof Geinitz from the far-off shore line of the upper chalk ocean at 

 Dresden. 



Small boring bivalves of the Modiola group are abundant, the 

 shells being still in their crypts. 



At Brickhill the Lamellibranchs are much less common than at 

 Upware ; only fourteen species are known there, and eight of these 

 belong to the Ostrwidce. 



Brachiopoda. 



The Upware Brachiopoda have been so thoroughly worked out 

 in the published works of Mr Walker and Mr Davidson that it is 

 not necessary here to describe them with the same detail as the 

 other groups. But since the publications of these authors appeared 

 the new workings at Brickhill have yielded us much fresh material 

 for work, including many new and interesting forms and some 

 additional species. 



Both the Upware and Brickhill Neocomian sea bottoms were 

 particularly rich in the 'lamp shells.' They grew so thickly 



