90 MANUAL OF THE MOLLUSCA. 



Helix fruticmn, living in France and Sweden. 



.. ruderata Germany. 



„ labyrinthica (Eocene) New England. 



Paludina marginata France. 



Corbicula consobrina Egypt and India. 



Unio littoralis France and Spain. 



On the other hand, some of the commonest living species 

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

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

 tiaries, viz. : — 



Glandina. 



Cyclotus. 



Nematura. 



Proserpina. 



Megalomastoma. 



Melania. 



Cylindrella. 



Craspedopoma. 



Melanopsis 



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), Moquin Tandon. 



Dalmatia, 



202 (197 „ 5 



5> 



), Bellotti. 



Denmark, 



95 (72 „ 23 



J> 



), Morch. 



Norway, 



62 (36 „ 16 



>1 



), Martens and Friele. 



Finland, 



41 (23 „ 26 



5> 



), Nylander and Nordenskjbld. 



Lapland, 



16 (10 „ 6 



» 



), Wallenberg. 



This table seems to show that the 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 G-ermany 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 

 northerly species are Limncea palustris, Fhysa fontinalis, Physa 

 hypnorum, and Succinea putris. 



Dr. Middendorff gives the following list of Siberian shells in 

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



Helix carthusiana, Irkutsk. Limnsea stagnalis, Bernaul, Irkutsk. 



Schrenkii, M. Tunguska, 58°.. „ palustris, „ „ 



hispida, Beresov. Bernaul. „ truncatula, „ Tomsk, 



ruderata, Stanowoj Mtn. „ leucostoma, Irkutsk, 



pura, „ Physa hypnorum, Bernaul ; TaimjTlande 



sub-personata, „; Ochotsk. Planorbis conieus, Bernaul; Beresov; 



Pupa muscorum, Bernaul. Kirgisensteppe, Altai. 



Zua lubrica, „ Planorbis complanatus, Altai. 



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



Limnaea G-ebleri, M. Beniaul. „ contortus, „ 



„ auricularia, Nertschinsk. „ vortex, „ 



„ ovata, Bernaul. „ leucostoma, „ 



„ Kamtschatica, Mid. „ nitidus, Irkutsk. 



„ peregra, Bernaul, Beresov. Bithynia tentaculata, Bernaul, 



