CLIMATE OF PLEISTOCENE PERIOD. 59 



conditions implied by the niolluscan fauna of La Celle are 

 precisely the same as those deduced by Count Saporta from a 

 study of the flora. The geographical distribution of the shells, 

 so different from that which now obtains, and the former wider 

 diffusion of certain forms, lead to the conclusion that the climate 

 of Northern France was formerly more equable, so as to permit 

 species, now widely separated, to live together. That it was 

 also a humid climate is proved by the general facies of the shells, 

 nearly all of them terrestrial, and the great majority such as 

 live in damp and shady places, some in humid woods about the 

 foot of trees, others upon marsh-plants and mosses, under stones, 

 or in moist earth. 



A somewhat similar suite of shells occurs in certain ancient 

 river-deposits of the neighbourhood of Paris, which are known 

 to geologists as " diluvium gris." M. Bourguignat gives a list 

 of 76 species, of which 36 are land-shells — the most abundant 

 forms being Helix nemoralis, H. arbustorum, Helix pidchclla, 

 Succinea putris, Bulimus montanus, Pupa muscorum, etc., all of 

 which occur in the beds at La Celle. They are associated as at 

 La Celle with Succinea joinvillensis, Cyclostoma lutetiana, and 

 other extinct forms, and with exotic species such as Helix 

 bidens. 1 



The calctufa and alluvial deposits of Canstadt in Wiirtem- 

 berg, contain, according to Klein, 50 species of land -shells, 

 and 21 of river-shells. Of these 50 species he recognises 36 

 as still living in the same region, 10 as occurring beyond it, 

 but still indigenous to Europe, and 4 as extinct. The species 

 which are most abundant are Helix arbustorum, H. nemoralis, 

 H. obvoluta, H. pulchella, H hispida, etc., Succinea putris, 

 Bulimus montanus, Clausilia parvula, Pupa muscorum, Pomatias 

 septemspiralc, etc., which occur along with Helix bidens, and 

 some extinct species, such as Zonites acieformis, and Succinea 

 elongata, Braun, — a form closely approaching to S. joinvillensis. 



1 For lists of shells in French river-deposits, see Memoire sur le diluvium de 

 Viry-Noureuil et les fossiles qu'il renferme (Paris, 1864), by l'Abbe Lambert ; 

 Bull. Soc. G60I. France, 2 Ser., t. xvii. p. 68 ; Belgrand's La Seine, t. i. p. 202. 



