Geology and Mineralogy. 77 



ocean through a narrow outer beach into the waters of Currituck 

 Sound as is formed by either the new or Ocracock Inlet to Pamlico 

 Sound now. With the closing ol the Currituck Inlet there was 

 the conversion of upwards of one hundred square miles of shal- 

 low salt to brackish water area to fresh water ; and it is within the 

 memory of men now living that the resultant changes were 

 immediate and striking. 



Previously the sound had been a valuable oyster bed. Within a 

 few years the oysters had all died out and their shells may now 

 be seen in long rows where they have been thrown out in dredg- 

 ing for a boatway in the Coinjock Bay, a southwestern extension 

 of the Sound. Further, there were such changes in vegetation as 

 brought countless thousands of ducks of species that had been 

 only occasional before. The salt water fishes were driven out 

 and fresh water fishes took their place. 



5. Papers on Dczmonelix, — The number of the University 

 Studies, published by the University of Nebraska, for January, 

 1897, vol. ii, No. 2, contains an important paper by E. H. Bae- 

 boue, on the history of the discovery of Da?monelix with notes 

 on the results of further study in regard to it. This paper is 

 accompanied by seventeen excellent plates showing the lorms in 

 great variety, the method of occurrence, and the microscopic 

 structure. The author feels entirely convinced that the forms 

 have organic origin, and are not to be explained as the burrows 

 of a rodent. A second paper by T. H. Marsland, iu the same 

 number, gives the result of chemical examination of the composi- 

 tion of the siliceous tubes. The analysis of different samples 

 varies somewhat widely, but the material is shown to consist to a 

 large extent of free hydrous-silicic acid with silicates of iron, 

 aluminum, manganese, calcium, and magnesium. 



6. Papers and Notes on the Genesis and Matrix of the Dia- 

 mond ; by H. Caevill Lewis. 8°, 72 pp., 3 pis. London, 

 1897. (Longmans, Green & Co.) — This volume consists of two 

 hitherto unpublished papers by the late Prof. Caevill Lewis ; 

 also a third compiled and edited from manuscript notes left by 

 him by Prof. T. G. Bo^ney. The first two papers were read 

 before the British Association. 



The work is chiefly petrographic in its nature and in a variety 

 of ways it is proved that the rock accompanying the diamonds in 

 South Africa is of igneous origin, a member of the peridotite 

 group, and that the diamonds have been formed by the contact 

 metamorphism of included fragments of carbonaceous shales. 

 Similar rocks from the United States are also described. The 

 editor differs from the author as to the precise method of occur- 

 rence of the igneous rock, while agreeing with him in other par- 

 ticulars. The whole forms an important and valuable addition to 

 our knowledge respecting rocks of this class and the origin of the 

 diamond, and students of this branch of science are much in- 

 debted to both Mrs. Lewis and the editor for giving these papers 

 to the public in such attractive form. l. v. e. 



