Geological Society of London. 381 



107 wliich have hitherto been unrecorded from beds of Neocomian 

 age. The following 10 species and varieties have been known pre- 

 viously only from recent deposits, viz. : — Kaplophragmium foliaceum, 

 Brady; Virgulina suhdepressa, Brady; Ehrenbergina pupa (d'Orb.) ; 

 Polymorphina sororia, Keuss, var. ciispidata, Brady ; P. oblonga, 

 Will. ; P. regina, Brady, Parker, and Jones ; Discorbina Bertlieloti 

 (d'Orb.) ; D. concinna, Brady ; D. Vilardeboana (d'Orb.) ; and 

 D. araucana (d'Orb.). The large number of forms new to the 

 Neocomian fauna is undoubtedly due to the fact that the deposits of 

 the Bargate series belong almost exclusively to the " Laminarian " 

 and " Coralline " zones. Taking into consideration the facts th?t 

 23 per cent, of the forms recorded are almost peculiarly Neocomian 

 types, that these added to known Cretaceous and Tertiary species 

 amount to 122, or 87 per cent, (the latter additions probably being 

 due to the circumstance that the Neocomian strata have not been so 

 extensively examined in regard to their rhizopodal fauna as might 

 have been desired), it is extremely probable that the microzoic fauna 

 of the Bargate series is almost entirely, though not quite (since we 

 have a few Jurassic species present), indigenous to the deposit. 



In conclusion, the author states his indebtedness to Prof. T. Eupert 

 Jones, F.R.S., and Prof. J. W. Judd, F.P.S. ; to Dr. W. F. Hume, 

 F.G.S., Dr. G. J. Hinde, V.P.G.S., Dr. J. W. Gregory, F.G.S., and 

 Graf Solms-Laubach ; and to George Murray, Esq., F.L.S., — for 

 valuable aid during the preparation of the present work. 



3. " On Deposits from Snowdrifts, with Special Reference to the 

 Origin of the Loess and the Preservation of Mammoth-remains." 

 By Charles Davison, Esq., M.A., F.G.S. 



When the temperature is several degrees below freezing-point, 

 snow recently fallen is fine and powdery, and is easily drifted by 

 the wind. If a fall of snow has been preceded by dry frosty 

 weather, the interstitial ice in the frozen ground is evaporated, and 

 the dust so formed may be drifted with the snow and deposited in 

 the same places. The snowdrifts as a rule are soon hardened by 

 the action of the sun or wind, and the dust is thus imprisoned 

 in the snow. As the snow decays, by melting and evaporation, 

 a coating of dust is extruded on the surface of the drifts, and, 

 increasing continually in thickness as the snow wastes away, is 

 finally left upon the ground as a layer of mud, which coalesces with 

 that of previous years. The de^Dosit so formed is fine in texture, 

 unstratified, and, as experiments show, mica-flakes included in it are 

 inclined at all angles to the horizon. 



The author describes several such deposits both in this country 

 and in the Arctic regions; and suggests (1) that the Loess is such a 

 deposit from snowdrifts, chiefly formed when the climate was much 

 colder, but still very slowly growing; (2) that Mammoths suffocated 

 in snowdrifts are subsequently embedded, and their remains pre- 

 served, in the deposits from them ; and (3) that the ground-ice 

 formation of Alaska, etc., is the remains of heavy snowdrifts when 

 the coating of earth attained a thickness greater than that which the 

 summer heat can effectually penetrate. 



