Notes, Reviews and Comments. 229 



Crosby, W. O. and M. L. Fuller — Origin of pegmatite. 

 Technology Quarterly, Vol. IX, No. ,4, pp. 326-356, Boston 

 December, 1896. 



The aqueo-igneous theory of the origin of pegmatite, the 

 characters of the acid pegmatites, their composition, the relations 

 of the composition to enclosing rocks, texture and crystallization 

 are presented. Then the igneous, aqueous, and aqueo-igneous 

 theories that have been advanced are discussed. We tbink that 

 writers are presenting the situation in a very fair light when they 

 conclude from their studies o{ pegmatite that : 



(i) " No sharp line of demarcation can be drawn between 

 dikes and veins." 



{2) " In a broad view of the early history of the earth, all 

 the sedimentary and vein rocks are, of course, secondary with 

 reference to the primitive igneous crust, but so are the igneous 

 rocks with which we are now acquainted " 



(3) " Probably none of the igneous rocks which have been 

 studied are truly primitive and their derivation in some cases 

 from sediments is claimed by many observers. We commend 

 this paper to all earnest students of Archaean geology. — H. M. A- 



BOLETIN DEL INSTITUTO GEOLOGICO DE MEXICO. Nums 

 4, 5.6. Bosquejo geologico de Mexico, Director, Jose G. 

 Aguilera, Mexico, 1897. 



We have just received the above work, which contains 270 , 

 pages of 4to letter press with a number of wood cuts and a 

 coloured geological map of Mexico. This work opens with an 

 appropriate " biographical sketch of Don Antonio del Castillo, 

 late Director of the Geol. Inst, of Mexico," by J. G. Aguilera, 

 followed by an introduction to the present volume and report 

 by the same author. Three chapters follow, bearing upon 

 the geological work carried on by R. J. Bullna, E. Ordonez and 

 J. G. Aguilera. This completes part i of the present volume. 

 The second part consists of a geological summary of the 

 Republic of Mexico, in which extensive lists of the fossil 



