44 BRITISH CRETACEOUS BRACHIOPODA. 



to assign any differences ; again PL II, fig. 3, from the Gault of Eolkstone, is undis- 

 tinguishable from the Chalk and Upper Green Sand forms; figs. 23 and 25 of PI. IV are 

 the same as found by Defrance, in the Green Sand of Havre, in France, and named by 

 him Ter. lima ; if any of these variable shapes had proved constant in any of the above 

 sedimentary deposits, we might have supposed them distinct, but in one, as well as in all, 

 the same variations are perceptible, and the only difference being that of colour, arising 

 from the matrix wherein they have been imbedded, which is white in the Chalk, grey or 

 blue in the Gault, and grey-yellowish or dirty-white in the Upper Green Sand. Such are 

 my views ; I may, however, be mistaken. The fortunate discoveiy of perfect interiors, 

 both from the Chalk and Upper Green Sand, was a circumstance unknown to M. D'Orbigny, 

 that author's figure in ' Pal. Fran.,' PL 514, fig. 8, being incomplete and incorrect. 



Plate IV, figs. 21, 22, and 25. From the Upper Green Sand of the neighbourhood of 



Warminster, nat. size, in the collection of Mr. 

 Cunnington ; fig. 22 is the largest specimen I have 

 seen. 

 „ V, fig. 4. Is a specimen from the Upper Green Sand of Cambridge, in the 

 collection of Mr. Carter, in this locality, as well as at near 

 Warminster ; many varieties of shape are perceptible, of which our 

 space does not permit of illustration. 

 „ IV, fig. 23. A specimen from the Chloritic Chalk of Chard, from the collection 

 of Mr. Moore. Mr. Morris has similar specimens from Chaldon ; 

 and the same may be seen in the British Museum, from Havre, 

 in France. 

 „ fig. 24. The original specimen of Ter. spinulosa (Morris), from the Gault of 



Folkstone, now in my collection. 

 „ fig. 24 c . An enlarged illustration ; we have also other specimens of this shell 



from the same Gault, proving the identity with those from the 

 Upper Green Sand and Chalk. 

 „ V, fig. 3. Is likewise from the Gault of Folkstone. 

 ,, fig. 3 C . An enlarged illustration. 



„ fig. 1. From the Grey Chalk, Maidstone, in the collection of Mr. Morris. 



,, fig. l a . An enlarged illustration. This is an exceptional form. 



„ fig. 2. From the same bed, between Folkstone and Dover. 



„ IV, fig. 15. From the interior of the smaller valve of a specimen from the Upper 

 Chalk, near Norwich. Mr. Carter has a similar specimen from 

 the Upper Green Sand of Cambridge. See also woodcut, figs. 5 

 and 6, in the Text. 

 „ fig. 16". A very young specimen from the Upper Chalk of Dover. 



„ fig. 16. Another young specimen from the Norwich Chalk, belonging to 



Mr. Woodward. 



