AUCELLA. 6'.) 



Remarks. — The English specimens have the median part of the valve apparently 

 less sharply marked off from the anterior and posterior parts than it is in the 

 examples figured by Hennig, but they agree in this respect with the figure given 

 by Peron. 



The specimens show some variation in obliquity and in their relative height 

 and length. The differences seen in the ornamentation are probably due, in part, 

 at any rate, to imperfections in the preservation of the surface layer of the shell. 

 Like Peron, I have seen no specimen of the right valve. 



Examples of this species are preserved in the Norwich Museum, in Dr. Black- 

 more's collection, and in Mr. Brydone's collection. 



Distribution. — Zone of Actinocamax quad ml us of East and West Harnham 

 (Salisbury). Zone of Belemnitella mucronata of Clarendon (Salisbury) and Norwich. 

 Chalk of Trimingham. 



Genus — Aucella, A. Kcyserlinij, 1846. 

 (' Keise in das Petschora-Land,' p. 297.) 



Aucella volgensis, Lahusen, 1888. Plate X, figs. 1 a-c, 2 a-c. 



1888. Aucella volgensis, J. Lahusen. Ueber die russischen Aucellen (Mem. du 



Comitc geol. Euss., vol. viii, No. 1), p. 

 38, pi. iii, figs. 1—17. 



1896. — A. P. Pavlow. Quart. Journ. Geol. Soc, vol. Hi, p. 549, 



pi. xxvii, fig. 1. 



1896. — — var. radiolata, Pavlow. Ibid., p. 550, pi. xxvii, fig. 2. 



Description. — Shell large, obliquely ovate, much higher than long, moderately 

 inflated, with regularly curving margin. 



Right valve of moderate convexity, flattened. Umbo relatively small, and 

 curving only slightly. Anterior ear triangular, with a deep, narrow byssal sinus. 

 Posterior ear indistinctly limited. 



Left valve very convex and rounded, the dorsal portion continued into a large 

 and prominent umbo which curves anteriorly. Postero-ventral part of valve pro- 

 duced and somewhat compressed. 



Surface of valves with concentric growth-ridges, sometimes produced into 

 lamella?, and forming regular curves. 



Measurements : 



Length 



Height of left valve (oblique' 

 Thickness (both valves) 



(1, 2) Spilsbv Sandstone, Donnington. 



(1) 



(2) 



45 



36 mm, 



66 



55 „ 



32 



. 22 „ 



