Reviews — Roemer's Erratic Blocks of N. Germany. 35 



bounding his route ; he has further combined the information ob- 

 tained from other travellers and from the natives; but even so the 

 mapping of the geological features of no small proportion of the 

 country must have depended upon bold generalizations. Whatever 

 may be the result of subsequent actual investigation by future 

 Chinese or European geologists, this preliminary attempt to lay 

 down the geological boundaries of this vast area cannot fail to be of 

 great advantage and assistance to later workers, and deserves the 

 warmest recognition. The maps are on the scale of 1 : 750,000 ; the 

 colouring emplo3 r ed for the different geological divisions is partly 

 similar to that adopted by the Geological Congress. This first part 

 of the Atlas is intended to accompany the second volume of the 

 author's great work on China, which has been already noticed in 

 the Geological Magazine. 1 G. J. H. 



III. — LETH^A ErRATICA, ODER AuFZATILUNG TJND BeSCHREIBUNG DER 

 IN DER NoRDDEUTSCHEN EbENE VORKOMMENDEN DlLUVIAL Ge- 

 SCHIEBE NORDISCHER SeDIMENTAR-GeSTEINE. Von FERDINAND 



Roemer. Mit 11 Tafeln und 3 Holzschnitten. Palasontologische 

 Abhandlungen heransgegeben von W. Dames und E. Kayser. 

 Zweiter Band. Heft 5. (Berlin : G. Reimer, 1885.) 



Letelea erratioa, or an Enumeration and Description of the 

 Diluvial Erratics of Northern Sedimentary Rocks occur- 

 ring in the Plains of North Germany. By Ferdinand Rcemer. 

 4to. pp. 173. With 11 lithographed plates and 3 woodcuts. 



TN the Boulder-clay which is so extensively distributed over the 

 plains of North Germany and Russian Poland, besides the frag- 

 ments of gneiss, granite, and other crystalline rocks, there are numer- 

 ous broken-up portions of sedimentary strata, many of which abound 

 in fossils. These fossiliferous erratics have long been studied by 

 German paleontologists, more particularly by the veteran author of 

 this work, and the present memoir, with its 11 lithographed plates 

 of the principal fossils occurring in the Boulder-clay, is intended as 

 a more complete description of them than that published by him in 

 1862. 2 



The author first gives a list of the principal memoirs which have 

 appeared on the subject since 1828, and then refers briefly to the 

 geological position of the Boulder-clay ; the state of preservation of 

 the boulders and fossils ; the geographical extension of the deposit ; 

 the different formations to which the erratics belong ; the original 

 localities from whence they come ; and the manner in which they 

 have been transported to their present positions. Following this, is 

 a detailed description of the different species of fossils, of the pre- 

 sent distribution of each in the Boulder-clay, and of the beds in 

 which the fossils now occur in other European areas. 



The fossiliferous erratics belong to the Cambrian, Silurian, 

 Devonian, Jurassic, Cretaceous, and Tertiary formations. The most 



1 Decade II. Yol. IX. p. 429. 



2 Zeitschrift der deutsclien geologischen Gesellschaft, bd. 14, pp. 575. 



