546 Scientific Intelligence. 



mate," by John M. Clarke, is especially interesting, because in 

 these markings the author has further confirmation of his con- 

 clusion that "the late Devonian was a period of cold which 

 brought the land ice down to what is now the edge of the sea at 

 the northeast [G-aspe], and may well have created conditions, 

 regardless of the alternation of the seasons, which would give 

 plenty of means for channeling the Devonian strands of New 

 York, by the movement of land ice toward the sea, or by the 

 landward thrust of the sea ice back from the water. ' ' 



R. Ruedemann also has a very important paper, Paleontology 

 of arrested Evolution. This is a study of the persistent or con- 

 servative genera and chiefly of invertebrates. Of these there are 

 506 genera out of a possible total of about 4000, or over 12 per 

 cent. It is among the lower classes of organisms, and again among 

 the lower forms within the subclasses, that are found the more 

 primitive genera with the greater percentage of persistent forms. 

 Restriction and specialization for narrow conditions of life lead 

 "to extinction when these conditions change." On the other 

 hand, the animals that live in the open ocean and in the abyss, or 

 under subterranean conditions, have more stable environments 

 and tend to show a remarkable persistence and immortality. 

 Sessile forms also tend toward persistence, and in the marine 

 waters persistent types are more common than in , fresh waters 

 and on the land. Originally the persistent types were the most 

 vigorous stocks. ' ' The evidence here gleaned from the persistent 

 types and equally supported by both groups of persistent types, 

 the persistent radicals and persistent terminals, leads necessarily 

 to the general conclusion that there is no inherent propelling 

 force of variation or of development, and that all evolution in the 

 last analysis is largely dependent on the exterior agencies sup- 

 plied by the ever changing physical conditions." c. s. 



2. Geology of the Oregon Cascades; by Warren Du Pre 

 Smith. Univ. of Oregon Bulletin, n.s., 14, No. 16, 54 pp., 1 pi., 

 1917. — The author points out that we know little "with certainty 

 about the formations and events prior to the Tertiary," and that 

 the West Coast geological events are similar to those on the other 

 side of the Pacific. "The three most striking instances of this 

 [similarity] are the period of Tertiary gold deposition, prac- 

 tically contemporaneous around the entire Pacific arc, the Eocene 

 coal formations, and the tremendous eruptions of basaltic and 

 andesitic lavas, which continue to this day, though not on so 

 extensive a scale as in the past. 



"The general conclusion is that the geology of the various 

 countries bordering on the Pacific must be deciphered and inter- 

 preted by duly considering the data from all these regions." 



c. s. 



3. The Evolution of Vertebrae, and The Osteology of some 

 American Permian Vertebrates. Ill; by Samuel W. Willis- 



