246 PROC. COTTESWOLD CLUB vol. xiii. (4) 



more distinct, and they begin earlier, so that they are 

 longer as well as broader ; the sulcus in the brachial valve 

 is less pronounced, and the pedicle valve is less convex. 



Remarks : — The differences from the Italian shell, R. 

 Meneojiinii, are particularly interesting, because that shell 

 is distinctly earlier in date. It is said to come from Middle 

 Lias, presumably hemera spinati. And in accordance with 

 its earlier date it shows less development of plicae than the 

 present species. The general build of the little Italian 

 shell is pretty much the same as the English one, and it 

 has a similar sulcus in the brachial valve ; but it is smooth 

 longer, and plicate later, while the sulcus is more distinct. 

 So the English species, which is, say two hemerse later, 

 shows a particular advance in development corresponding 

 with its date ; it has carried on and elaborated the develop- 

 ment of plicae, just as we find in the case of the Terebra- 

 tula-Jiinbria series. 



Locality and Stratum: — From a small exposure of Upper 

 Lias Clay on Standish Park Farm, below Standish Beacon, 

 the beds yielding Harpoceras falciferiim, etc. 



Date of Existence: — Falciferi hemera, Harpoceratan 

 Age (Upper Lias). Rh. Meneghinii is from Middle Lias, 

 that would be probably Spinati hemera of the Deroceratan 

 Age, about two hemerae earlier than R. standishensis. 



IV. Independent Development of Biplication 



3. TEREBRATULA WITHINGTONENSIS, 5. Buckman. 



PI. XIL, figs. 8—12. 



Description : — A small, globose, uniplicate, or biplicate Terebratu- 

 loid, with a short, obliquely truncate beak, and an intiated umbo. 



Distinction : — From Terebr. Etheridgii — the uniplicate 

 form is rather more circular, more globose, and has a less 



