326 Eeviews — Triibner's Geological Map of Heidelberg. 



rocks. It occurs as sheets and as nodules, generally in beds. It is 

 homogeneous and consists of silica, not so pure, however, as is the 

 case with quartz. This silica, once in solution, has been accumulated 

 round sponges, etc., changing some of the surrounding chalk into its 

 own substance. 



Flint has yielded fit material for fashioning into tools or weapons, 

 the application of blows and pressure producing sharp flakes, the 

 substance is also capable of being dressed into definite shapes. 



The surfaces of broken flints suff'er changes from exposure and 

 from moisture, becoming opaque, and often shining when affected by 

 alkaline water. 



The note concludes with a list of the chief works relating to the 

 subject. W. W. 



3. — Lowe, W. B. Geological Section [Eeport of]. Sep, Bugby 

 School of Nat. Hist. Soc.for 1872, pp. 47-49 (2 plates). [1873.] 

 Notes the occurrence of the rare Discina Holdeni in the Lias at 

 Hillmorton Pits, of bones in various later deposits, and of various 

 other fossils. Gives a section of Drift over Lias at Eugby Pit, and 

 sections of gi-avel, etc, along a sewer in Hillmorton and Clifton 

 Eoads. A detailed account of the section at the Victoria Lime 

 Works to a depth of 72 feet, through Lias clay and stone, is also 

 given in plate vi. W. W. 



4. — Salter, J. W. A Catalogue of the Cambrian and Silurian 

 Fossils in the Geological Museum of the University of Cam- 

 bridge. With a Preface by the Eev. Prof. A. Sedgwick, and 

 a Table of Genera, etc., by Prof. J. MoBnis. 4to. pp. xlviii. 

 and 204. Cambridge, [1873]. 

 The greater part of the long preface is taken up with an account 

 of the Cambro-Silurian controversy, in which Prof. Sedgwick fully 

 states his own views and their history. 



This is followed by a Table of the Classification of the Lower 

 Palaeozoic rocks according to Sedgwick, Murchison, Jukes, Lyell, 

 Phillips, and the Geological Survey. Prof. Morris contributes a 

 summary of the contents of the Catalogue, and a Table of the Eange 

 of the Genera. 



The Catalogue is illustrated by woodcuts and arranged stratigraphi- 

 cally, beginning with the lowest beds. An elaborate geological map 

 (woodcut) of Portniadoc Estuary, with a multitude of faults, is given 

 at p. 9. There are many paragraphs on the stratigraphical relations 

 of the beds, etc. W. W. 



ISE "VI IB "VsT" S. 



I.^ — Geognostische Kakte dek Umgegend von Heidelberg. 

 Bearbeitet von Dr. E. W. Benecke und Dr. E. C. Cohen. 

 Blatt II. SiNSHEiM. Strassburg : Karl J. Triibner, 1874. 



THIS second part of a very elaborate map of the geological features 

 of that portion of the Grand-Duchy of Baden which lies to 

 the traveller's immediate left hand during a railway journey from 



