90 MANUAL OF THE MOLLUSCA. 



Helix fruticiim, living in France and Sweden. 



.. niderata Germany. 



„ labyrinthica (Eocene) New England, 



Paludina marginata France. 



Corbifula consobnna Egypt and India. 



Unio littoralis France and Spain. 



On tlio other hand, some of tho commonest living spccioa 

 have not been found fossil ; e.g. Helix aspersa, pomatia, and 

 cantiana. Several genera only occur fossil in the older ter- 

 tiaries, ^•iz. : — 



Glandina. Cyclotus. Nematura. 



Proseri)ina. Megalomastoma, Melania. 



Cylindrella. Craspedopoma. Melunopsis. 



The following estimates have been made of the number 

 of air-breathing molluscs inhabiting the various countries of 

 Europe : — 



France, 202 (176 land, 26 fresh-water), Moquiu Tandon. 



This table seems to show that tho Pulmonifera are most 

 numerous in the warmest parts of Europe, and that their 

 numbers decline, as far as species are concerned, as we ap- 

 proach the Polar regions. Thus, in the Mediterranean area 

 there are 800 species, in Germany 200, in Norway 50, in Lap- 

 land 16. Hitherto, only 23 species have been obtained from 

 European countries north of the Arctic circle. The most 

 northerlj' species are Limncea pahistris, Physafontinalis, Physa 

 hypnorum, and Succinea puiris. 



Dr. Middendorff gives the following list of Siberian shells in 

 his Sibirische Reise (Band II. th. 1. Petersb. 1851) : — 



Helix carfhusiana, Irkutsk. Limnsea stngnalis, Bernaul, Irkutsk. 



Schrenkii. M. Tunguska. 55". „ pahistris, „ „ 



hispida. Beiesov. liernaul. „ truncatula, „ Tomsk, 



ruderata, Stanowoj Mtn. „ leucostoma, Irkutsk, 



pura, „ Physa liypnorura, Bernaul ; TaimjTlanue 



sub-personata, „ ; Ochotsk. Planor'uis corneus, Bernaul; Beretovj 



Pupa muscorum, Bernaul, Kirgisensteppe, Altai. 



Zua lubrica, „ Planorbis coniplanatus, Altai. 



Succinea putrls, „ ; Irkutsk. „ albus, Bernaul, „ 



Limnsea Gebleii, M. Bernaul. „ contortus, „ 



„ auricularia, Nerlschiiisk. „ vortex, „ 



„ ovat I, BernauL „ leucostoma, „ 



„ Kamtschatica, Mid. „ niiidus, Irkutsk. 



„ peregra, Bernaul, Beresov, Bitlij-nia tentacula^a, Beroou]. 



