8. V. Wood— Origin of the Loess. 339 



witli Observations on the Dinosauria of the Trias/' ^ remarlcs on the 

 Dinosauria of the Urals. He suspects Deuterosdurus will prove to 

 be a Dinosaur. This, however, falls within Owen's Theriodontia, as 

 does Bhopalodon. 



I venture to throw out the suggestion that the tooth now described 

 indicates a reptile of the order Dinosauria. 



All true reptilian (i.e. distinct from anaphibian) remains from this 

 formation in Russia which I have seen or heard of are theriodontine. 

 Dinosaurian remains are as yet unknown. The miner is the sole 

 agent we can rely upon for disentombing these Permian reliquiae. 

 The absence of natural sections in the vast grass-covered steppes, 

 and the reputation which the rocks of this age bear for paucity of 

 organic remains, as well as the knowledge that the few which are 

 derived from them are of a connective character, linking together 

 the Palgeozoic and Mesozoic epochs, invest every additional, though 

 isolated, discovery with unique interest. 



EXPLA]S^ATION OF PLATE VIII. 



Fig. la. Canine of an unknown Theriodont reptile from Levsky mine, Kargalinsk 

 steppe, lb. Ic. Id. transverse sections, le. crenation of border mag- 

 nified. I am indebted to Mr. Thos. Eickard for the loan of this tooth. 



Fig. 2. Incisor of Deuterosaurm biarmicus (Eichwald), from Eoshdestvensky mine, 

 Kargalinsk steppe. 



Fig. 3. Supposed Dinosaui'ian tooth from the same locality. 



The subjects of Figs. 2 and 3 were generously presented to me by Mr. 

 Mr. Eobert Fletcher of Lothbury. All the figiires are natural size. 



II. — 0^ THE Origin of the Loess. 

 By Seaeles V. Wood, F.G.S. 



yAEIOUS theories have been advanced to explain the origin of 

 the Loess of Europe, Asia, and North America, the latest 

 having been that of Mr. Ho worth, in the pages of this Magazine. 



Although possessing no knowledge of this formation, outside of 

 England, beyond that derived from the descriptions of those per- 

 sonally acquainted with it, I have for some time thought that the 

 Loess has originated from an agency of which I detect evidences 

 among those phenomena of the Newer Pliocene period in England 

 wdiich I have endeavoured to trace in detail in a memoir on that 

 subject laid before the Geological Society of London ; but as the 

 Loess in general is not discussed by me in that memoir, I venture to 

 offer a few observations on the subject of it for the consideration of 

 the readers of the Geological Magazine. 



It appears to me that in all arctic countries not occupied with 

 land ice, and where therefore the soil is permanently frozen to a 

 great depth, and only the surface for a depth of two or three feet 

 annually thaws, conditions must obtain, of which in temperate lati- 

 tudes, save so far as the sliding away of an Irish bog may offer a 

 partial parallel, nothing furnishes any analogy. 



Although trees and vegetation grow freely during the summer on 

 this small thickness of thawed surface, it is obvious that no water 

 1 Quart. Joum. Geol. Soc. 1870, p. 72. 



