I 



1901 S. S. BUCKMAN — BRACHIOPODA 247 



pronounced fold ; and a truncate beak. From Tcrebr. 

 nolgrovicnsis, the biplicate form is rather less globose, and 

 the folds are not so pronounced. From T. Eudcsi, the 

 obliquely truncate beak. 



Remarks : — The three specimens of the present species 

 which have been figured show the development of the uni- 

 plicate form (fig. 10), the incipient biplicate form (fig. Il), 

 and the definite biplicate form (fig. 12). They indicate 

 that the species is derived from a uniplicate form of the 

 Terebr.-Ethcridgii type, and that it develops towards a 

 pronounced biplicate form like Terebr. notgroviensis. It 

 is therefore a strictly transitional form, and a connecting 

 link of marked importance between two very distinct 

 species. It is the parent of Terebr. notgrovieiisis, preced- 

 ing it in time, as this species occurs in the Pea-grit, that 

 one in the Oolite Marl of the same neighbourhood. The 

 length of time is represented by a deposit of some 80 to 

 100 feet of limestone. T. Etheridgii is not exactly the 

 parent of this form, because it has not the truncate beak 

 like this one ; but it is a homoeomorph of the uniplicate 

 form. T. Eudesi develops its folds in a different manner ; 

 and it belongs to a more sphaeroidal stock : it is a homoeo- 

 morph of the biplicate form. 



The specimen of Terebr. notgrovieiisis, figured by me 

 in the Proceedings of this Club, Vol. ix.,* is really an ex- 

 treme (senile) form. It is rather a degenerate form with 

 somewhat pronounced plications. Other specimens from 

 the Oolite Marl are more robust, rather larger, and have 

 less developed plications. 



Locality and Stratum : — The cuttings on the Midland 

 and South-Western Junction Railway near Withington 

 (Gloucestershire), in Pea-grit. 



Date of Existence : — Murchisonce hemera. 



* Plate iii., fig. 5. 1887. 



