184-6.] PRESTWICH ON THE ISLE OF WIGHT TERTIARIES. 239 



these beds. M. Melleville's* distinctions are still more positive. 

 I do not pretend to say that the Bognor beds are the exact equiva- 

 lents of the ' Lits coquilliers' ; but as these latter exhibit a varied and 

 large marine fauna in part peculiar to the lower Eocene group in 

 France, so in England do the Bognor beds maintain a fauna, 

 certainly more restricted, but nevertheless equally distinctive and 

 characteristic of that epoch. 



As before mentioned, the Hampshire series exhibits a group of 

 genera rich in individuals, but few in species, such as Vermetus, 

 Pinna^ Pholadomya, &c., indicating a marine littoral or a shallow 

 sea deposit. The French beds, on the contrary, in the north and 

 northeast of the Paris basin (in the central and southern districts 

 this group thins out), contain many more genera, mostly rich in 

 species, and show an admixture of freshwater shells of the genera 

 Melanopsis and Paludina with numerous estuary shells, such as 

 Cerithium, Ampullaria, Cyrena, &c., aj^sociated with marine forms, 

 many of them inhabiting greater depths than those found in the 

 Bognor rocks. As we have, therefore, evidence of conditions varying 

 from a river-mouth to a tolerably deep sea-bottom, it follows that, 

 from the more numerous zones of depth thence resulting, we might 

 expect a greater variety of testacea than we meet with in the more 

 uniform shallow sea deposit of the Bognor rocks. As corroborating 

 this view of the influx of fresh waters into a sea, for the most part 

 shallow, may be noticed an interesting fact mentioned by Professor E. 

 Forbes in his Report on the Invertebrata of the ^gean Seaf , namely, 

 that, with few exceptions, individuals of the same species are there 

 dwarfish compared with their analogues in the Western Mediterra- 

 nean, and he attributes this fact to the influx of the brackish waters 

 of the Black Sea. Now the very same result is observable in the 

 'Lits coquilliers'; for M. d'Archiac, in his valuable paper on the 

 Geology of the Departement de I'Aisne (Mem. de la Soc. Geol. de 

 France, vol. v. p. 271), states that they are distinguished, not only 

 by distinct fossils but by varieties, constantly smaller, of species oc- 

 curring in the calcaire grossier. 



Of the species of testacea found in the Bognor beds in Hampshire 

 and Sussex (thirty to thirty-two in number), the following eighteen 

 occur in the 'Lits coquilliers' and ' Sables inferieurs' J: — 



Anomia lineata, Sow. (? A. tenuistriata, Globulus sigaretinus, 5ow. (Natica si- 



Lam.) garetina, Def.) 



Cassidaria carinata, Lam. Infundibulum trochiforrue, Sow. (Ca- 



Fusus rugosus, Lam. ? lyptrsea trochiformis, var. Lam.) 



* Annales des Sciences Geologiques, vol. ii. 



t Report of Brit. Assoc. 1843, p. 152. 



+ One of the most constant and characteiistic fossils of the lower beds of the * Lits 

 coquilliers ' is the Nummulites planulatus of M. d'Archiac {N. eleffans, Sow.). 

 Another characteristic species is the Bifrontia laudincnsis. In this country they 

 have only been found higher in the scries, and the latter is common at IJrackles- 

 ham ; but this at present is an anomaly. The Panopfpa intormedia, a diaractcr- 

 istic species from the Bognor beds, is I believe identical with the Corbula dubia 

 of Deshayes, a fossil of this series in France. 



VOL. II. PART I. R 



