CHAP. IX. MIGRATIONS OF QUADRUPEDS. 157 



suburbs of that city. By an account published at the time, 

 we find that the mammalia which accompanied the musk 

 buffalo were the mammoth and tichorhine rhinoceros, with the 

 horse and ox;* but I can find no record of the occurrence of 

 a hippopotamus, nor of Elephas antiquus or Rhinoceros lep- 

 toi'hinus, in the drift of the north of Germany, bordering the 

 Baltic. 



On the other hand, in another locality in the same drift of 

 North Germany, Dr. Hensel, of Berlin, detected, near Qued- 

 linburg, the Norwegian Lemming (Myodes Lemmus), and 

 another species of the same family called by Pallas Myodes tor- 

 cpiatus (by Hensel, Misothermus torquatus), — a still more arctic 

 quadruped, found by Parry in latitude 82°, and which never 

 strays farther south than the northern borders of the woody 

 region. Professor Beyrich also informs me that the remains of 

 the Rhinoceros tichorhinus were obtained at the same place. f 



As an examjile of what may possibly have constituted a 

 more southern fauna in the valley of the Thames, I may 

 allude to the fossil remains found in the fluviatile alluvium 

 of Gray's Thurrock, in Essex, situated on the left bank of the 

 river, tAventy-one miles below London. The strata of brick- 

 earth, loam, and gravel ex^^osed to view in artificial excava- 

 tions in that spot are precisely such as would be formed by the 

 silting up of an old river-channel. Among the mammalia 

 are Elephas antiquus, Rhinoceros leptorhinus (R. megarhinus 

 Christol), Hippopotamus major, species of horse, bear, ox, 

 stag, &c., and, among the accompanying shells, Cyrena flumi- 

 nalis, which is extremely abundant, instead of being scarce, 

 as at Abbeville. It is associated with TJnio littoralis, fig. 22, 

 also in great numbers, and with both valves united. This 

 conspicuous fresh-water mussel is no longer an inhabitant of 



* Leonhard and Bronn's Jahrbuch, gischen Gesellschaft, vol. vii. 1855, 

 18.36. p. 215. p. 548, &o. 



I Zeitschrift der Deutschen Geolo- 



