



pe(^ti^:n. 







Measurements : 













(1) 



(2) 



(•'5) 



(4) 



Lengtli 



36 



2.5 



22 



15 mm. 



Heio-lit 



40 



27 



20 



H) „ 



159 



(1) B. hilcraJis zone, Speetou. 

 (2, 3) B. jaculum zone, Speeton. 



(4) Claxby Ironstone, Benniworth Haven. 

 'J hesc measurements are approximate onlj, on account of the inipcrfedidu of the specimens. 

 Considerably larger examples than (4) occur in the Claxby Ironstt)n('. 



AflJiiitles. — I have seen only a few specimens of this species, and most of them 

 are very imperfect, consequently I am unable to make a detailed comparison with 

 alHed forms. The species which appears to approach most nearly P. striato- 

 jmnetains is 7*. Mnriiii, de Loriol;^ it is found in the Portlandian of Swindon, 

 Hartwell, etc., and seems to differ from /'. sfrinfo-jniuctatiis in l)eing less equilateral, 

 owing io the greater proportionate lengtli and inward curvature of tlie antero- 

 dorsal margin ; the ribs are also, on the average, more numerous and ch)ser 

 together, but vary somewhat in this respect. 



r. vinjattis, Nilsson, and P. curvattis, Geinitz (see below), are also related to /'. 

 sfriat()-])unctafiis. 



Re marls. — Romer figured no examples of this species, but erroneously referred 

 to Goldfuss' figure of a Jurassic form (/*. /r/?.s). A small form found rarely in the 

 Gault of Folkestone is perliaps referal)le to P. striato-iymictatus. 



Tijpcs. — From the Hils-conglomerate and Hils-clay of Schandelah, Schoppen- 

 stedt, and Elligser Brink. D'Orbigny's specimens were obtained from the Aptian 

 of St. Dizier (Haute Marne). 



Distribution. — Speeton Clay (zones of B. lateralis, D 1, and of B. jaculam, C 11) 

 of Speeton. Claxby Ironstone (zone of Bet. lateralis) of Benniworth Haven. 

 ? Upper Gault (zone viii) of Folkestone. 



Recorded l)y Topley (1875) from the Atherfield Beds of Peasmarsh and East 

 Shalford, and from the Folkestone Beds of Folkestone. Recorded by Moi-ris from 

 the Lower Greensand of Folkestone. 



Peoten (CAMrxoNECTEs) CUEVATUS, Gciiiitz, 181;3. Plate XXIX, figs. 7 a, h; Plate 



XXXVII, tig. 1(). 



1833. Pecten arcuatus, A. Goldfuss. Petref. Germ., vol. ii. i>. 50, pi. xci, fig. G 



(non Nilsson). 

 ? 1841. — — F.A.Bihner. DieVerstein.d. nord-deutsch. Kreidegeb., 



p. 51. 



1 De Loriol and Pellat, " Portlandien de Boulogno-sur-Mer " (' Mem. Soc. Phys. et d'Hist. nat. 

 Geneve,' vol. xix, 1866), p. 107, pi. x, fig. 6. 



