B. K. Emerson — Northfieldite. 217 



Si0 2 , as a border to a coarse museovite biotite granite. It is 

 fine-grained granitoid with only a few flakes of museovite.* 

 It is suggested in the cited paper that the quartzose border bed 

 represents the surplus of the eutectic which is present in the 

 central granite. It seems possible that the action of a large 

 amount of water upon the superficial portion of the exception- 

 ally acid magma may have promoted the differentiation of this 

 ultra-acid variant much as a pegmatite dike passes into a 

 quartz vein. 



A similar highly acid aplitic rock has been found in the 

 border of the Milford granite around Uxbridge. An occur- 

 rence one and a half miles north of Mill ville contained 87'51 

 per cent SiO Q . It forms a layer of considerable thickness 

 between the normal Milford granite which contains 77 to 78 

 per cent of Si0 2 and an outer border band of diorite schist. 



Amherst, Mass. 



* Dwerryhou.se, A. E., Quart. Jour. Geo. Soc, vol. lxv, p. 60, 1890. 



SCIENTIFIC INTELLIGENCE. 



I. Geology and Mineralogy. 



1. Water Reptiles of the Past and Present ; by Samuel 

 Wendell Williston. Pp. vii, 251, text figs. 1-1 31. University 

 of Chicago Press, 1914. — In this volume Professor Williston 

 summarizes our knowledge of the reptiles which have become 

 adapted to aquatic life. He also includes a classification of 

 reptiles which differs in several respects from those lately pro- 

 posed, principally because of the discovery in Europe, South 

 Africa, and North America of so many strange forms which 

 throw doubt on all previous attempts to trace out the genealogies 

 of reptilian orders. The fifth chapter discusses the adaptations of 

 reptiles to aquatic life and the modifications which water-living 

 brings about, comparing the reptiles in their structural changes 

 with other important aquatic types. The following chapters 

 take up the water-loving reptiles in orderly sequence. Professor 

 Williston's books are always interesting and authoritative, and 

 the one under review is no exception to the rule. 



e. s. L. 



2. Illinois Coal Mining Investigations. — The State Geologi- 

 cal Survey (University of Illinois) in cooperation with the U. S. 

 Bureau of Mines and the U. S. Geological Survey has recently 

 issued the following Bulletins: 



No. 10. Coal resources of District 1 (Longwall); by Gilbert 

 H. Cady. Pp. 149; 11 pis., 27 figs. 



No. 11. Coal resources of District VII (Coal No. 6 west of 

 Duquoin anticline); by Fred H. Kay. Pp. 233; 4 pis., 47 figs. 



