182 SUPPLEMENT TO THE BRITISH 



In 1851 I considered the Inferior-Oolite shell under description and the Oxford-Clay 

 W. impressa to be varieties of a same species. Many specimens of the two appeared to 

 be undistinguishable. Dr. Oppel and Mr. E. Deslongchamps believe them to be distinct; 

 and, as they are found in different horizons, they had, perhaps, better be considered, at 

 least provisionally, as such. Mr. Deslongchamps states that " the very great and regular 

 curvature or convexity of its larger valve, and its smaller size distinguish it from 

 W. carinata, with which it is found associated, and which it resembles in the concavity 

 of its smaller valve." 



W. Meriani is broadly suboval, and either as wide as long, or a little longer than 

 wide ; broadest posteriorly, tapering anteriorly, and slightly indented in front. Ventral 

 valve deep and keeled ; beak much incurved, and truncated by a small circular foramen 

 lying close to the umbone of the smaller valve ; beak-ridges sharply defined. Dorsal 

 valve slightly convex, especially posteriorly, and divided into two portions by a deepish 

 median groove to which the lateral portions of the valve slope on either side. Interior 

 not known ; but, no doubt, the loop was long as in Waldheimia. Surface smooth, and 

 marked only by concentric lines of growth. 



Length of a rather large specimen 12, width 10, depth 8 lines. 



05s. — I cannot quite agree with Mr. E. Deslongchamps' statement that W. impressa 

 is more elongated than W. Meriani. It is so only occasionally. W. Meriani occurs in 

 the Inferior Oolite, or zone of Am. Humphresiana. It is common at Ravensgate Hill, 

 near Cheltenham, rare near Sherborne, and at Bradford Abbas, &c. In France it is not 

 abundant in Normandy, but is common at Niort and Saint Maixent (Deux-Sevres), near 

 Avallon (Yonne), and Macon (Soane-et Loire) according to Deslongchamps. Also at 

 Thurnan, Bopfingen, Gommelshausen, &c, Swabia. This species is allied to the 

 Neocomian species W. Mppopus, Romer. 



169. Waldheimia impressa, Von Buck. Dav., Ool. Mon., p. 33, PI. IV, figs. 9 and 10 



(not 8) ; Sup., PL XXIV, fig. 32. 



Mr. J. F. Walker informs me by letter that he and Mr. A. Wanklyn have micro- 

 scopically examined the shell-structure of W. impressa and W. Meriani, and that they 

 found that the canals traversing the shell in W. impressa, from the Oxford Clay, were 

 comparatively larger and closer than in W. Meriani from the Inferior Oolite of 

 Cheltenham. 



Mr. Deslongchamps states at p. 239 of his ' Brachiopodes Jurassiques ' that W. 

 impressa occurs, in France, in the beds characterised by Am. Lamberti (Oxford 

 Clay). Some fine examples from St. Clements, Oxford, are preserved in the Oxford 

 Museum. W. impressa is found in the Oxford Clay at St. Ives near Huntingdon, and 



