328 Reviews — An Inierglacial 'Period in Central Russia. 



Cyrtoidea, 55 sp. ; Steplianoidea, 8 sp., and Larcoidea 3 species. 

 Only 13 species are common to Jurassic and Cretaceous rocks. 



The author seems justified in considering tliese siliceous radio- 

 larian rocks as deposits of deep-sea character, comparable with the 

 radiolarian oozes of the present oceans, and it remains for those who 

 oppose this view to show wherein the difference consists. 



In the accompanying 25 plates excellent illustrations of the new 

 forms are given, enlarged to the scale of 300-450 diameters. It 

 would have been better if the scale of enlargement had been given 

 with each figure, for comparisons made with the measurements 

 given in the text show that in some cases they are drawn on a 

 much smaller scale than that stated. 



Dr. Riist deserves the thanks of all palseontologists for his arduous 

 researches on the Mesozoic and Paleeozoic Radiolaria, which are 

 completed with this memoir. Not the least difficulty in this pursuit 

 is to obtain material, for siliceous rocks, like those containing 

 Eadiolaria, have until lately been considered as barren of fossils, and 

 consequently have been unnoticed by collectors. The preparation 

 of microscopic sections likewise involves considerable labour, and 

 the author states that 5000 were made for the purpose of this 

 Memoir. The study of these small organisms is only now beginning, 

 and judging from the fact that in a single hand-specimen of rock in 

 which the forms are well preserved, fifty new species may be found, 

 there can be little doubt that in number and variety fossil Radiolaria 

 will prove in nowise behind those living at the present day. 



G. J. H. 



IV. — Anzeichen einer intekglaziaren Epoche in Central-Euss- 

 LAND. (Umgebungen des Dorfes TroYzkoje, Gouv. Moskau.) 

 Von N. Krischtafowitsch. Bulletin de la Soc. imperiale des 

 Naturalistes de Moscow, N.S. Tome IV. 1890, No. 4, pp. 527-547. 



Indications of an Interglacial Period in Central Russia. 

 (Village of Troizkoje, near Moscow.) By N. Krischtafowitsch. 



IN the high banks on the right side of the Moskwa river, at the 

 village of Troizkoje, about 10 kilometres from Moscow, there 

 are exposed some beds of lacusti'ine derivation containing numerous 

 plant and animal remains, including bones of the Mammoth, which 

 are covered by typical Glacial deposits, and on this account have 

 been supposed to be of pre-Glacial age, and compared with the 

 Forest Bed of Norfolk. This lacustrine formation has been studied 

 by several well-known Russian geologists during the last fifty yeai's, 

 and lately the author of this paper, accompanied by Professor and 

 Madame Pavlow, made a more thorough examination of the locality, 

 and by removing the debris at the base of the river bank ascertained 

 that the lacustrine beds rested on glacial materials of the same 

 character as those above them, thus showing that thej' were inter- 

 Glacial instead of pre-Glacial in age. It had been assumed by 

 previous writers that the fresh-water beds rested directly on the 

 Upper Jurassic sandstones which form the bed-rock in this region. 



