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



Distinction : — From Z. Leckenbyi (Walker), the more 

 transverse shape, and particularly the truncate beak. 



Genetic relations: — With Z. Leckenbyi, and Z. Wit- 

 chelli, S. Buckman. It precedes the former in time dis- 

 tinctly, being sometimes as much as 100 feet lower. The 

 two species named as its descendants express the change 

 of shape from transverse to much elongate. 



Localities and Stratum: — Gloucestershire, Crickley 

 Hill; Bull Bank, Miserden ; in Pea-grit. 



Date of Existence : — MnrcJiisonce hemera. 



Notes. — The most transverse specimen is from Miser- 

 den : it measures 30 mm. across and 26 mm. in length. 

 The largest specimen from Crickley measures, length and 

 width, 35 mm. It shows a more overhanging beak like 

 that of Z. Leckenbyi, so that with age it approaches that 

 species in this character, as would be expected. 



Young Z. Leckenbyi have the proportions and appear- 

 ance of Z. circnlaris. 



The Pea-grit of l^andwick Ash, near Stroud, which is 

 about the date of the Lower Freestone of Cheltenham, has 

 yielded some broad specimens with rather overhanging 

 beaks ; they are really the forms connecting Z. circnlaris 

 and Z. Leckenbyi. 



13. ZEILLERIA ANISOCLINES, 5'. Buckman, sp. n. 



PL XIIL, figs, iia, b, c. 



Description : — Inequivalve, sub-ovoid to sub-pentagonal in outline, 

 brachial valve nearly flat, pedical valve per-convex. Beak projected, 

 overhanging the umbo ; beak ridges fairly defined, sub-acute ; foramen 

 small. 



Comparison : — With the heterochronous homoeomorph 

 Terebratula subomalogaster. 



Remarks: — The inequivalve appearance of the shell 

 viewed sideways, which suggests the specific name, gives 

 a longitudinal section the figure of a D. 



