19G CRETACEOUS LAMELLIBRANCHIA. 



Non 1842. Pecten pulchellus, P. Mat/teroti. Cat. Foss. du Bouclies-du-Eli6ne, 



p. 186, pi. XXX, figs. 4 — 6. 



— 1853. — — L. Reeve. Conch. Iconica, vol. viii, pi. xxxii, fig. 142. 



— 1872. — — H. B. Geinitz. Das Elbthalgeb. in Sachsen (Palaeon- 



tographica, vol. xx, pt. 2), p. 33, 

 pi. X, figs. 2 — 4. 



— 1877. — —A. Fritsch. Stud, im Gebiete der bohni. Kreide- 



format. : II, Die Weissenberg. u. 

 Malnitz. Schiclit., p. 136, fig. 130. 



— 1893. — — B. Michael. Zeitsclir. d. deutsch. geol. Gresellsch., 



vol. xlv, p. 243. 



Description. — Shell small, oval, rounded, height equal to, or slightly greater 

 than the length ; nearly equilateral, the postero-dorsal margin a little longer than 

 the antero-dorsal. Convexity of valves small. Apical angle about 103°. Ears of 

 moderate size, unequal. 



Right valve witli a variable number (t-Aventy-three to forty-four at the margin) 

 of broad, flattened, radial ribs, separated by much narrower, shallow grooves ; in 

 approaching the umbo some of the ribs become united in pairs. Near the anterior 

 and posterior borders ribs are small or absent. Both ribs and grooves are marked 

 by numerous fine radial striae, which, in the middle of the valve, are parallel with 

 the ribs, but cut them more and more obliquely in passing toward the anterior and 

 j)Osterior margins, which they meet at acute angles. Anterior ear longer than 

 high, with the outer margin rounded and a rather small sinus ; posterior ear 

 smaller, triangular, higher than long, outer angle obtuse ; both ears with radial 

 strife like those on the valve, and the anterior ear sometimes with a few concentric 

 ridges also. 



Left A'alve Avith narrow, elevated, sharply-limited ribs, some of which (often 

 alternate ones) do not reach the neighbourhood of the umlio. Ribs small or absent 

 near the anterior and posterior margins. Grooves between the ribs broad and 

 deep, marked by radial strias like those on the right valve. Summits of ribs 

 slightly serrate. Ears triangular, the posterior a little smaller than the anterior 

 and with the outer angle obtuse ; both ears with radial striae. 



M('asnvement!< : 



(1) (2) 



Length . 2()-5 . 15-0 

 Height . 20-5 . IG'O 



(1 — 4) from Trimingham. 



Aijlnities. — 1\ linvdUm, Nilsson, is a left valve of 1\ puIcheUufi. F. spurius, 

 Goldfuss, from Haldem, of which the type is in the Munich Museum, has been 

 shown by Hennig to be identical with P. imlcliellus. The form from the Planer- 

 kalk of Strehlen referred ])y Geinitz to P. jmlchellnf^ is regarded by Schliiter, 



(3) 



(4) 



12-5 



10-5 mm, 



L'3-0 



11-0 „ 



