394 Mr. S. S. Buckman on Jurassic Brachiopvda. 



But Mr. C. D. Slierborn, to whom I am indebted for much 

 bibliographic assistance, and whose invaluable help I gladly 

 acknowledge, solved tlie difficulty. lie pointed out that 

 d^Orbigny was quoting from the French edition of Sowerby 

 (by Agassiz), wherein the figures of the plates were re- 

 numbered — often in misapprehension of Sowerbj^s intention, 

 it may be noted. But pi. ci. fig. 5 of the French edition 

 equals pi. ci. fig. 4 of the original : it depicts the shell from 

 the Lias of Pickeridge. That becomes the type of T. sartha- 

 censis : it does not matter that d\)rbigny assigned it to 

 anotlier formation, or that he probably confounded with it 

 various other species. 



R. Tate in 'The Yorkshire Lias' (Tate and Blake) 

 rightly stated the case about d'Orbigny's T. sarthacensis, only 

 he did not explain that author's quotation of fig. 5 instead of 

 fig. 4. So Davidson was still mucii puzzled (vide remarks 

 Suppl. Jur. Brach., Pal. Soc. pp. 165, 166) and he retained 

 the name perfo7'ata. Tate again was quite right in his state- 

 ment that Davidson had figured the wrong fossil (namely 

 T. ornithocejihala, Sow., fig. 4=7\ sarthacensis, d'Orb.) as 

 Sowerby's type of T. ohovata. For, spite of Davidson''s pro- 

 tests (Suppl. p. 166), his pi. V. fig. 16 shows that he has 

 done this. 



Tate mentions T. hispidula, Simpson, as a Middle Lias shell 

 very near to T. perforata ; in fact, he classes it as such under 

 the name T. sarthacensis. But such Middle Lias shells as 

 I have seen like this are separable by a broader form and a 

 ratlier larger foramen. 



Another ^>e?;/(;r«to-like form occurs in the Middle Lias: it 

 was figured by Quenstedt as T. 7iumismalis ovalis. It is 

 distinguished by a larger foramen and by not showing a 

 squared front margin. These are exactly the characters 

 wliich d'Orbigny quotes as distinguishing his T. crithea 

 from T. sarthacensis, so that there is little doubt that 

 T. crithea is the designation for this Middle Lias shell. 

 True, d'Orbigny places it in Toarcian, but he cites many 

 other Middle Lias shells in that stage. 



The species may now be catalogued as under : — 



9. Ornithella crithea (d'Orbigny), 1850. 



T.d. 1850. d'Orbigny, Prodrome, p. 258. no. 271 ; Terehratula crithea. 

 T.f. None. 

 T.L Brulon. 



H. "Toarcien," but Wiynchonella tetraedia andi?/*. thalia are quoted 

 from this same " Toarcien " [Piiensbachian]. 



Remarks. — We may take as T.f. of this shell Terehratula 



