JURASSIC AND TRIASSIC BRACHIOPODA. 173 



Several curious malformations of this species have been found, some showing a lobed 

 condition, approaching that in the group of T. diphga. 



154. Waldheimia digona, Sow., sp. Dav., Ool. Mon., p. 38, PI. V, figs. 18 — 24; 



and Sup., PI. XXII, figs. 21, 22. 



Nothing new, with the exception that Mr. Walton found a specimen showing long 

 spines rising from the outer edge of the principal branches of the loop, as may be seen in 

 the figure we have added to this Supplement. Here, also, as in W. obovata, we meet 

 with exceptionally shaped specimens, in which the front line, instead of being straight, is 

 convex and rounded, or sometimes even indented. It occurs in the Great Oolite and 

 Bradford Clay at Bradford, and at Tetbury Road Station. Mr. Darell Stephens found it 

 in the Bradford Clay, associated with Bh. Boueti and a small var. of T. intermedia, at 

 Burton, Bradstock. 



155. Waldheimia bucculenta, Sow., sp. Dav., Ool. Mon., p. 55, PI. XIII, fig. 8 ; 



and Sup., PI. XXII, fig. 23; and 

 PI. XXIV, figs. 23, 24, 25. 



I have but little to add to the description I have already published of this variable 

 species. Mr. J. P. Walker has been able to settle its stratigraphical position in the 

 passage-bed of the Lower Calcareous Grit of Appleton-le-Street, four miles from Malton, 

 in Yorkshire. He has also found it at Filey in the same horizon. A black line along the 

 umbone of the smaller valve indicates that it is a Waldheimia. This species is associated 

 with W. Hudlestoni, Ter. Filey ensis, and Bh. Thurmani. W. bucculenta occurs also in 

 the Elsworth Rock. Specimens of this fossil from that deposit may be seen in the 

 Woodwardian Museum, Cambridge, and one was obtained by the late Mr. Leckenby 

 from the Cornbrash of Scarborough (Sup., PL XXIV, fig. 23), which I cannot distinguish 

 from some of the varieties of the shell under description. It is not, however, always an 

 easy matter to distinguish some exceptional forms of W. bucculenta and W. obovata, 

 var. Stiltonensis, which seem to be closely allied ; it is therefore possible that this 

 Cornbrash specimen may be an extreme form of the variety Stiltonensis. 



W. bucculenta has been found by Mr. Rigaux in the Oolite Corallienne d'Herdin 

 l'Abbe, near Boulogne-sur-Mer, also at the Mont des Boucardes. During a recent visit 

 to Cambridge Mr. E. Rigaux examined the Elsworth Rock and recognised it as the 

 equivalent of his Calcaire d'Houllefort, the stratigraphical position of which is immediately 

 above the Oxford Clay bed containing Wold, impressa and Terebratula insignis. This 



