39S Scientific Intelligence. 



ing is so designed as to throw into relief the areas of the sea- 

 bottoms above 1000 fathoms. This map will be of much value 

 to paleogeographers. Even though Thomson realizes that the 

 map is not yet nearly final, it leads him to recognize nineteen 

 separate and distinct geographic districts with their marine 

 faunas. Each one of these districts has from one to twenty- 

 seven species, and ten of them have living brachiopods. The 

 others are wholly devoid of them. The latter appear to be as a 

 rule oceanic or volcanic islands, though it is curious that a great 

 continental mass like Madagascar should be devoid of living 

 brachiopods. 



Thomson says that the greatest future scientific increase of 

 brachiopod distribution is to be gleaned rather from a survey of 

 the "little known submarine banks of the Southern and the 

 Pacific ocean bottoms than from a further Antarctic expedition. 

 If these banks have arisen by subsidence of previous lands, 

 remains of coastal faunas such as brachiopods are to be expected. 

 If, on the other hand, they represent recent diastrophic uplifts 

 of formerly deeper portions of the ocean floor, no such faunas 

 can occur. . . There is thus a practical method of testing the 

 theory of the permanence of ocean basins" (42). 



Thomson finds that the present distribution of austral living 

 brachiopods has not changed much in the larger geographic 

 sense since the Miocene. They owe their present distribution 

 to a more ancient time when means of intercommunication 

 between the lands bordering the South Pacific Ocean was better 

 than at present. The times of these former land connections 

 seemingly were in "the late Jurassic or early Cretaceous and in 

 the late Pliocene and post-Tertiary, but not in the Oligocene- 

 Miocene" (6). as. 



4. Pelecypoda of the St. Maurice and Claiborne stages; by 

 G. D. Harris. Bull. Amer. Pal., No. 31, 1919, 268 pp., 60 pis.— 

 Professor Harris has now been collecting and studying the 

 Eocene Mollusca since 1892, and in this volume he describes the 

 bivalves of the two stages beneath the top one, the Jackson stage. 

 The work is dedicated to the statesman and paleontologist, Tru- 

 man H. Aldrich, who is the connecting link between the first 

 paleontologist to describe Claiborne shells, Timothy A. Conrad, 

 and the workers of the present. 



In the present work are described about 85 established genera 

 and 255 recognized species and varieties. The author, however, 

 had to study about 613 forms, the difference being due to syno- 

 nyms or erroneous generic references. There are but two new 

 genera, Mauricia and Pachecoa, and of new species and varieties 

 there are 57. The author is to be congratulated upon his per- 

 sistence in doing so much good in making known the early Ter- 

 tiary Mollusca, especially as he has done this without much help 

 from any one, even in the illustrating and printing of his pub- 

 lications, c. s. 



