PTERIA. 63 



Rern&rks. — In England this species has, up to the present time, been definitely 

 recognised in the Actinoeamax quadratus zone only. 



The specimen figured by Romer is relatively higher than most of the English 

 examples, but in other characters there is close agreement. 



Pteria seminuda (Dames) ' resembles Pterin tenuicostata, but appeal's to differ 

 in the ribs on the left valve being of more nearly uniform size, and in the presence 

 of distinct ornamentation on the right valve. 



Type. — The type is stated by Romer to have come from the Lower Chalk of 

 Lindner Berg, near Hanover, but according to Dr. J. Bohm the horizon is really 

 the quadratus Chalk. 



Distribution. — Zone of Actinoeamax quadratus of West Harnham, near Salisbury, 

 and Sewerby (Yorkshire). Upper Chalk (? A. quadratus zone) of Coddenham 

 (Suffolk), Wells (Norfolk), and Huston Parva (Yorkshire). 



Sub-genus — Psetjdoptera, F. B. Meek, 1873. 



(' 6th Ami. Eep. U.S. Geol. Survey of the Territories,' p. 489; Meek, ' Invert. Cret. and Tert, Foss. 

 U. Missouri ' (Eep. U.S. Geol. Survey, vol. ix, 1876), p. 29.) 



Pteria (Pseudoptera) subdepressa (d'Orbigny), 13o0. Plate IX, fig. la, b. 



1845. Avicula depressa, E. Forbes. Quart. Journ. Geol. Soc, vol. i, p. 247, pi. iii, 



fig. 7 (non A. depressa, Miinster, 1841). 

 1850. subdepressa, A. (V Orbigny. Prodr. de Pal., vol. ii, p. 119. 



1854. ■ — depressa, ,/. Morris. Oat. Brit. Foss., ed. 2, p. 163. 



1855. subdepressa, G. Cotteau. Moll. Foss. de l'Yonne, p. 104. 



1869. — F. J. Pictet and G.Campiche. Foss. Terr. Cret. Ste. 



Croix (Mati'r. Pal. Suisse, ser. 5), 

 p. 70. 

 1871. F. Stoliczka. Palseont. Imlica, Cret. Fauna S. India, 



vol. iii, p. 398. 

 Remarks. — This species is very imperfectly known at present. It resembles 

 /'. haldonensis from the Upper Grcensand of Haldon (see below) but is easily dis- 

 tinguished by the strong concentric ridges; it also appears to be relatively longer 

 and less convex. 



Type. — In the Museum of the Geological Society (Xo. 2050). 

 Distnbution. — Lower Greensand (Crackers) of Atherfield. Recorded byTopley 

 from the Atherfield Clay of Peasmarsh and Shalford. 



1 'Zeitsehr. d. deutsch. geol. Gesellseh .,' vol. xxvi (1874), \>. 765, pi. \.\i, tig. 3; Notling, 'Die Fauna 

 d. lialtiscli. Cenonian.' ( Palseont. AHiandl., vol. ii, 1885), p. 21, pi. iii. figs. 7, 8. 



