PECTEN. 189 



1841. Pkcten Beaveri, i'^ A. R'niner. Die VL-rsteiu. d. nord-deutsch. Kreidegeb., 



p. 54. 

 1850. — ? Beaveri, ^. fZ'0/7%H(/. Prodr. de Pal., vol. ii, p. Kiy. 

 — — jUGOsus, /. de C. Sowerhy, in F. Dixon. Geol. Sussex, p. 347 (p. 



382, ed. 2), pi. xxviii, fig. 26. 

 1854. — Beaveri, /. Morris. Cat. Brit. Foss., ed. 2, p. 175. 

 1863. — — A. V. StrombecJc. Zeitschr. d. deutscli. geol. Gesellsch., 



vol. XV, p. 108. 



1870. — — F. J. Pictet and G. Campiclie. Foss. Terr. Crct. Ste. Croix 



(Mater. Pal. Suisse, ser. 5), pp. 214, 218. 



1871. — — F. Stoliczka. Palaeont. Indica, Cret. Fauna S. India, 



vol. iii, p. 428. 



DescrijAloii. — Shell large, tliin, oval or nearly circular; height usually slightly 

 greater than length ; margins evenly rounded except at the junction with the 

 ears. Valves compressed, nearly equal, slightly inequilateral. A})ical angle large, 

 from 118° to 125°. Ears long, low, a little unequal. 



Right valve with broad radial ribs, which have sharp and sometimes slightly 

 irregular summits and gently sloping sides ; there are also similar smaller ribs, 

 which do not reach the umbo. The ribs are smaller anteriorly and posteriorly. 

 The surface of the valve is ornamented with fine, close-set, concentric, linear 

 ridges, and sometimes with radial ridges. Anterior ear with a well-marked sinus, 

 ornamented with scaly ribs except near its junction with the valve. Posterior 

 ear smaller, outer angle nearly a right angle ; surface with libs, sometimes ol)scured 

 by concentric lamellse. 



Left valve with about seventeen main ribs, which are narrow, elevated, and 

 sharp, sometimes slightly serrate at the summits ; separated by broad furrows. A 

 smaller I'ilj is often introduced in the middle of the furrow at a distance from the 

 umbo, and on the sides of the ribs other still smaller ribs may occur. Anteriorly 

 and })osteriorly the main libs become smaller. The ribs and furrows are crossed 

 by many fine, close-set, regular, concentric ridges, which are seen most distinctly 

 in the furrows. Anterior ear a little more elevated than the posterior ; both with 

 radial ribs and sharp outer angles. 



. 88 



(1, 2) Chalk Marl, Folkestone. 



(3) „ „ Meldreth. 

 (4, 5) Totternhoe Stone, Burwell. 



(6) H. suhglohosus zone, Cherry Hintou. 



Ajjinitics.—r. (lepn'ssus, Goldfuss, seems to be scarcely distinguislial)le from 

 Beaveri. The specimen figured by Goldfuss as P. Beaveri does not show the 



Measurements : 



(1) 



(2) 



Length 



. 81 . 



, 80 



Height 



. 80 



. 88 



(i-^ 



(•"') 



I'i) 



100 . 



00 . 



100 nuu. 



100 . 



98 



. 109 „ 



