Heviews — A. J. Jukes- Brotcne — Upper Chalk of England. 279 



found it upon the study of the special fauna whicli the beds contain. 

 Thus, where Micrasters and Echinocorys are the predominant fossils, 

 we must base our zones on the succession of different species of these 

 Echinoderms ; elsewhere the Hippurites or other shells may furnish 

 the requisite data. But when the various local or regional classi- 

 fications have been thus established, and we wish to compare them 

 with one another, then they can be referred to the standard strati- 

 graphical scale which I propose to establish by means of the succession. 

 of Ammonite-faunas." 



Mr, Hill continues his series of observations on the microscopic 

 structure and components of the Upper Chalk in chapters xxii and 

 xxiii, the lists of Foraminifera being supplied by Frederick Chapman. 

 Mr. Hill finds the microscopic structure of the typical Chalk Eock 

 from Dorset and Wiltshire so characteristic that it is hardly possible 

 to mistake it for chalk from any other horizon. A slice cut from 

 the rocky chalk at the base of the H. planus-zone at Pinhay shows 

 all the characteristics of Chalk Kock ; and where the Chalk Eock is 

 absent, as in Kent, Surrey, and Sussex, and the zone of H. planus 

 consists of rough, lumpy, and nodular chalk, the nodules near the 

 base of the zone present a similar structure to that of the Chalk 

 Eock. On the other hand, the Chalk in which Holaster planus has 

 been found in Norfolk, Lincolnshire, and South Yorkshire, differs 

 entirely in structure both from the Chalk Eock and from the nodular 

 chalk of this zone. 



The authors find from an examination of the bathymetrical 

 conditions prevailing during the formation of the Upper Chalk 

 that there is distinct evidence of a shallowing of the chalk sea, 

 during the deposition of the Holaster planus-zone, succeeded by a 

 gradual deepening which culminated possibly during the deposition 

 of the Marsiqnte-zone, again to be succeeded by a progressive 

 shallowing up to the final passage of the Chalk into the Tertiaries. 

 While not presuming to affix a definite limit to the depth of the 

 sea during Ilarsupite times, the diagram accompanying the Eeport 

 suggests 700 fathoms as the probable extent of the depression. 

 Dr. Smith Woodward's researches among the fishes of the Chalk 

 have shown that " the majority of the deep-sea fishes of the Cre- 

 taceous period are more or less closely related to the Scopeloids 

 and Berycoids, which still form so conspicuous an element in the 

 abyssal fauna." They possess luminous organs. 



We are glad to notice that chapter xxv is devoted to " Economic 

 Products of the Chalk," a subject omitted in voL ii. The officers 

 of the Geological Survey have exceptional opportunities for amassing 

 this kind of information, which is not only of importance to the 

 public but tends to the completeness of their work. We looked 

 in vain in vol. ii for a sketch of the important industry in 

 Portland cement, which occupies so large a business feature in the 

 Medway area, and it is but briefly mentioned in vol. iii. 



The " Physical Features of Chalk Districts " forms an interesting 

 chapter, and the " Water Supply from the Chalk," even in so 

 condensed a form, is of great general importance. In this latter 



