Royal Society. 57 



win to distinguish the widely different forms of the variable species 

 of Cirripedia ; and in the case of British Mollusca, they may be 

 retained with advantage in such genera as Pisidium, Anodonta, 

 Littorina, &c. ; but there is surely much reason to question the ad- 

 visability of introducing varietal nomenclature on slight deviations of 

 form and colour, in the wholesale manner which we find in this 

 volume. For instance, there are distinguishing titles given to no 

 less than five modifications of the well-known Cochlicopa (Zua) lu- 

 brica. These varieties are characterized as follows : — 

 "Var. 1. hyalina. Shell greenish-white. 



Var. 2. lubricoides, Fe'r. Shell smaller and more slender. 



Var. 3. viridula. Shell shaped like the last variety, but greenish- 

 white. 



Var. A.fusca. Shell smaller and thinner, reddish-brown. 



Var. 5. ovata. Shell much smaller, and oval ; spire shorter." 

 The views of the author are at variance with those of previous 

 writers upon the subject of geographical distribution. It is his opi- 

 nion that the provinces as constituted by Milne-Edwards, Woodward, 

 and Forbes are all too limited in area, and that the fauna of Europe 

 should be divided into two provinces only — North European and 

 South European. The division between these provinces he would 

 mark by a " line drawn in the meridian of Bordeaux, which may be 

 assumed as an arbitrary point of demarcation between the two ex- 

 tremes of climate in Europe," and which roughby defines the limits 

 of the growth of the olive in "France. A table at the conclusion of 

 the volume shows the distribution of the British land and freshwater 

 shells in these two provinces, their presence or absence in a fossil 

 state in the Upper Tertiary formations, and their extra- European 

 range. The illustrations consist of nine plates, which contain figures 

 of the animal and shell of each genus described. 



In conclusion, we cordially recommend this work to conchologists, 

 and look forward to its completion, believing that the portion which 

 relates to the marine species is yet more required than that which is 

 now before us, and that its publication will give a healthy stimulus 

 to the study of the British Mollusca. 



PROCEEDINGS OF LEARNED SOCIETIES. 



ROYAL SOCIETY. 



March 27, 1862. — Major-General Sabine, President, in the Chair. 



" Theoretical Considerations on the Conditions under which the 

 Drift Deposits containing the Remains of Extinct Mammalia and 

 Flint- implements were accumulated ; and on their Geological Age." 

 By Joseph Prestwich, Esq., F.R.S., F.G.S. 



In his former paper on the subject of the Flint-implements*, the 

 author postponed the consideration of the theoretical questions, to 



* See Annals, ser. 3. vol. iv. p. 230, for abstract ; Phil. Trans. 1860, p. 277, for 

 the entire memoir. 



