44:6 Scientific Intelligence. 



explained in difference of geological horizons. In Sweden 

 (Oeland) the Upper Cambrian passes gradually into the Ordovi- 

 cian while in Estland a sandstone and black-shale zone of no great 

 thickness represents the last of the Cambrian and reposes con- 

 formably upon the Lower Cambrian. Upon the former then 

 follow glauconitic sands and glauconite-bearing dolomites hold- 

 ing a fauna that can be compared in America only with the 

 highest members of the Lower Ordoviciau. The sequence in 

 Estland then seems to continue without any marked break to the 

 end of the Ordovician, but in southern Sweden these higher hori- 

 zons are certainly not faunally present in Oeland. They are, 

 however, sparingly represented to the north in the Leptaena Kalk 

 of Dalarne. These regions have therefore dissimilar sediments 

 of various transgressions of a sea from the south and west over- 

 lapping on the Baltic shield of Suess. With England and Ire- 

 land there is far less in common, there being but 11 species, and 

 nearly all of these are from the uppermost Ordovician or Lyck- 

 holm (F) formation. With the Lower Ordovician of England 

 there seems to be nothing in common, but this must be ascribed to 

 the very backward condition of British Ordovician paleontology. 



c. s. 



4. The Stratigraphy of the Western American Trias; by J. P. 

 Smith. Festschrift zum siebzigsten G-eburtstage von Adolph v. 

 Koenen, 1907, pp. 377-434. — In this important paper Professor 

 Smith gives a general summary of the western American marine 

 Triassic formations, their faunas, and the probable waterways of 

 invertebrate migrations. These inter-migrations are complex and 

 in the main are based on abundant ammonite evidence. Having 

 shown that migrations take place from the Mediterranean across 

 the Atlantic aud Mexico to California and, in the opposite direc- 

 tion from India around the northern shores of the Pacific, the 

 author then takes up the later migrations of Mesozoic and Ceno- 

 zoic time. The hindrance to continuous northern Pacific migra- 

 tions during geological time he thinks is due to the deep channel 

 east of Kamchatka, through which now courses the cold water cur- 

 rent from the Bering Sea. This barrier has been effective at dif- 

 ferent times and, at others, has been considerably shallowed 

 through elevation. "A rise of 200 meters would close Bering 

 Strait, and about one-half of Bering Sea, giving a shoreline coin- 

 ciding approximately with a great circle. It would then leave 

 the Aleutian chain as a long narrow peninsula reaching out from 

 Alaska towards Siberia, separated from Kamchatka by a narrow 

 but deep channel ; while the mainland of Alaska and Siberia would 

 be united by a broad land-bridge. This change in the height of 

 the land would cut off ail influx of cold water from the Arctic 

 Sea." c. s. 



5. Remarks on and Descriptions of new Fossil Uuionidce 

 from the Laramie Clays of Montana ; by R. P. Whitfield. 

 Amer. Mus. Nat. Hist., Bull, xxiii, 1907, pp. 623-6 2S ; pis. 38-42. 

 — Herein are described eight new species of U~nio, six other 



