90 MANUAL OF THE MOLLUSCA, 
Helix fruticum, living in France and Sweden. 
ee) TUGCTALAs ssc csveen-se ae Germany. 
», labyrinthica (Eocene) New Englanc. 
Paludina marginata ......... France. 
Corbicula consobrina ......... Egypt and India. 
Unio littoralis | s2..c-..c0es scene . France and Spain. 
On the other hand, some of the commonest living species 
have not been found fossil; e.g. Helix aspersa, pomatia, and 
eantiana. Several genera only occur fossil in the older ter- 
fiaries, 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), Mloquin Tandon. 
Dalmatia, 202(197 ,, 5 s ), Bellotti. 
Denmark, 95 (72 ,, 23 ss ), Morch. 
Norway, 52(36 ,, 16 ~ ), Martens and Friele. 
Finland, 41(23 ,, 26 5 y, Nylander and Nordenskjold. 
Lapland, 16(10 ,, 6 A ), Wallenterg. 
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 Germany 200, in Norway 40, 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, Physa 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. Limneza stagnalis, Bernanl, Irkutsk. 
»  schrenkii, M. Tunguska, 58°. “1 palustris, a oc 
» hispida, Beresov. Bernaul. “ truncatula, ,, Tomsk. 
» ruderata, Stanowoj Mtn. re leucostoia, Irkutsk. 
5» pura, 5 Physa hypnorum, Bernaul; Taimyrlance 
s» sub-personata, ,,; Ochotsk. ‘Planorbis corieus, Bernaul; Beresov; 
Pupa muscorum, Bernaul. Kirgisensteppe, Altai. 
Zua lubrica, 55 Planorbis complanatus, Altai, 
Succinea putris, 33 Lrkutsk. as albus, Bernaul, ,, 
Limnza Gebleri, M. Bernaul. “p contourtus, 4, 
a9 auricularia, Nertschinsk. “p vortex, or 
9 ovata, Bernaul. “f leucostoma, ,, 
Fe Kamtschatica, Mid. nitidus, Irkutsk. 
5s peregra, Bernanl, Beresov. Bithynia tentaculata, Bernal, 
