254 PROC. COTTESWOLD CLUB VOL. xiii. (4) 



8. (3) TEREBRATULA imitator, S. Bitckman, nom. nov. 



PI. XIII., fig. 6a, b, c. 



1877. WaLDHEIMIA EMARGINATA, Davidson (non 



T. eiiiarginata, Sow.) Brachiopoda in the 

 Inferior Oolite, &c. ; Proc. Dorset Field 

 Club, Vol. I., pi. iii., figs. 10, II. 



1878. Waldhhimia EMARGINATA, Davidson^ Oolitic 



and Liassic Brach. (Monogr. Palseont. Soc), 

 Vol. IV., Suppl., pi. xxiii., figs. 5, 6. 



Descriptioji :—k somewhat ovoid, globose shell. The side and 

 front margins thickened, the latter indented, with a lobe each side of 

 the indentation. Junction of valves straight or nearly so, not definitely 

 waved as in biplicate forms. Beak short, stout, separated from umbo, 

 showing deltidial plates ; no definite beak ridges ; foramen somewhat 

 large, circular. 



Comparison : — Zcilleria bicornis is so much a homoeo- 

 morph that Davidson figured specimens of T. imitator 2C!\^ 

 of that species as examples of Waldheimia emarginata. 

 Zeilleria snkoniuta is an even more remarkable homffio- 

 morph. Specimens are identical in shape, the beak is the 

 only point of difference, but of course the septum in 

 Z. snbco7niiita is indicated by a dark line in the umbo. 



A heterochronous homoeomorph is T.eudesiana, another 

 bilobate Terebratuloid. 



Distinction : — From Terebr. endesiana, the larger size 

 of the shell, the less globular form, the flatter brachial 

 valve, the straighter side margin, the beak less incurved 

 and definitely separated from the umbo. 



Genetic relations : — Probably with T. sphceroidalis, 

 whereof it is what may be called a bilobate, not a biplicate, 

 development. Its likeness to T. endesiana does not indi- 

 cate direct genetic affinity, but parallel development over 

 again from a similar stock. 



Localities and Stratum: — Dorset: Broad Windsor, and 

 Bradford Abbas, in the upper beds. 



