248 PROC. COTTESWOLD CLUB vol. xili. (4) 



4. TEREBRATULA HYALINA, 5. Btickman, sp. n. 



PI. XIII., figs. 8a, b, c. 



Descriptio7i : — Valves convex, the pedicle valve the most. Outline 

 of shell ovoid, and in lateral aspect globose, elongate. Front margin 

 elevated to form a single fold, level across. Beak small, short, close 

 pressed to umbo. Foramen small. 



Distinction : — From Terebratrda radstockensis, the 

 smaller foramen, the curved lateral margin, the frontal 

 fold. From Terebr. shirbiirniensis, longer, less globose, 

 less distinctly plicate. 



Comparison : — Many of the Zeilleria? are more or less 

 homceomorphs. 



Remarks : — This extremely elegant species, with a 

 glassy-looking and apparently very thin test, has much 

 resemblance to deep sea forms of the present day. The 

 clayey marl wherein it is found probably indicates deeper 

 water conditions than the limestone of the same date in 

 the Bradford Abbas neighbourhood — where the species 

 has not yet been obtained. 



This is almost an incipiently biplicate form, closely con- 

 nected with the sphaeroidal stock of which T. shirbiir- 

 niensis and T. Eiidesi are examples. Though later than 

 the former, it is in some respects less developed, as in its 

 plication ; in other respects — departure from the sphaeroi- 

 dal to the ovoidal form — it is more developed. 



Locality and Stratum : — Somerset, Horethorne Down, 

 in a bluish, clayey marl ; scarce. 



Date of Existence : — Discitce hemera. 



5. TEREBRATULA SIDERICA, S. Biickman, sp. n. 



PL XIII., figs, iia, b, c. 



Description : — \"alves insequi-convex, the brachial valve being nearly 

 flat. Side margin curved, front margin biplicate; but the plicae begin 

 rather abruptly. Beak short, rather stout, somewhat hanging over 

 umbo, hiding deltidial plates ; foramen oval, with a kind of labiate ex- 

 tension over umbo. 



