332 Scientific Intelligence. 



find that the maximum of their specific differentiation occurred 

 in the Middle Cambrian, where there are 31 genera and 335 spe- 

 cies. In the Upper Cambrian there are 224 forms. The great 

 bulk of differentiation took place in the four families Paterinidaa, 

 Obolidse (main stock), Acrotretidae, and Billingsellidae, though 

 there are 14 families of brachiopods in the Cambrian. 



On page 160 there is a very interesting table giving the species 

 as they occur in the different types of sediment. Out of 500 

 forms only 150 have been found in more than one kind of sedi- 

 ment. In limestone occur 310 forms, in shale 199, and in sand- 

 stone 240. Common to limestone and sandstone there are 44, to 

 limestone and shale 50, to shale and sandstone 28, and to all three 

 types of sediment 33. We see therefore the justification of the 

 author's conclusion, that as a rule " each species is confined to one 

 type of sediment" (159). The "facies" is hence an important 

 factor in paleontology. 



Great pains has been taken to locate each fossil in the geolog- 

 ical scale in such a way that future paleontologists can always 

 determine the detailed horizon, even though the classification of 

 the formations changes fundamentally. In the same way the 

 bibliography of each species is annotated so as to give the student 

 the essentials in each reference. 



Fossil brachiopods preserving the setae fringing the mantle are 

 exceedingly rare, and one is figured here on page 362 as Iphidella 

 pannula. It is from the Burgess shale of British Columbia, the 

 locality that has furnished Dr. Walcott with so many other won- 

 derfully preserved fossils. 



The general shell characters of the Brachiopoda are described 

 on pages 296-315, the evolution and classification on pages 316— 

 326, and the genera and species on pages 327-810. 



This work will always be the book for students of Cambrian 

 Brachiopoda and the foundation upon which all phylogenies of 

 the lamp-shells will be built. It is all the more remarkable that 

 a work of so great importance should have been produced by one 

 whose time is so much occupied in administration and in the pro- 

 motion of American science. c. s. 



4. United States of North America / by Eliot Blackwelder, 

 University of Wisconsin, Madison. (Handbuch der Regionalen 

 Geologie ; herausgegeben von Prof. Dr. G. Steinmann, Bonn, und 

 Prof. Dr. O. WuYkens, Jena. VIII Band, 2 Abteilung.) Pp. 

 258, figs. 81. Heidelberg 1912 (Carl Winter's Universitatsbuch- 

 handlung). — This volume, written in English, is the first to 

 appear of the projected series dealing with the western hemis- 

 phere. The complete series is planned to cover the whole world; 

 this work is, therefore, of unusual interest. It contains a clear 

 and well-proportioned summary of the geology of the United 

 States classified under the topics of morphological summary, strat- 

 igraphy and formations, outline of geological history, orographic 

 elements, economic geology, summary of literature, table of 

 names of formations. Geologists of the United States will find 



