Geology. 509 



Sweden is most important, as it gives the first definite suggestion 

 of a base for the Ordovician in the section along the Canadian 

 Pacific Railway west of the Continental Divide. In Sweden the 

 Ceratopyge shale and limestone are now by general assent placed 

 at the base of the Ordovician, and with our knowledge of the 

 stratigraphy of the upper portion of this section as determined by 

 Mr. Allan I am inclined to agree with him in placing, at least 

 tentatively, the boundary between the Cambrian and Ordovician 

 at the summit of the Ottertail limestone and the base of the 

 Goodsir formation" (230). c. s. 



3. The Sardinian Cambrian Genus Olenopsis in America ; 

 by Charles D. Walcott. Smithsonian Misc. Col., 57, No. 8, 

 pp. 239-249, pi. 36, 1912. — The author here describes three 

 species of Olenopsis derived from the upper part of the Lower 

 Cambrian of Pennsylvania and from the passage beds at the base 

 of the Middle Cambrian in Montana, Alberta, and British 

 Columbia. The genus was originally discovered in Sardinia, 

 where its exact stratigraphic position remained undetermined. 

 Walcott shows in this paper that the Sardinian species probably 

 is of the time of the strata "beneath the Middle Cambrian 

 Paradoxides beds, either in passage beds from the Lower to the 

 Middle Cambrian, or in the upper beds of the Lower Cambrian" 

 (239). c, s. 



4. Middle Cambrian Branchiopoda, Malacostraca, Trilobita, 

 and Merostomata ; by Charles D. Walcott. Smithsonian 

 Misc. Col., 57, pp. 148-228, pis. 24-34, 1912. —In this preliminary 

 paper of extraordinary interest are described 1 new order, 5 new 

 families, 5 old and 19 new genera (of Branchiopoda, Opabinia, 

 Beanchoilia, Yohoia, Bidentia, JSTaraoia, Burgessia, and Wap- 

 tia ; of Malacostraca, ITurdia, Tuzoia, Odaraia, .Field ia, and 

 Camarvonia; of trilobites, Marrella, J^athorstia, Mollisonia, 

 and Tont.oia / of Merostomata,- Molaria, Habelia, and JEmerald- 

 ella), and 31 new species. Nearly all are derived from the Burgess 

 shale of' Middle Cambrian age near Field, British Columbia. 

 This shale has furnished the author with no less than 56 genera 

 derived from a block of shale not over 6 by 40 feet in area and 

 7 feet in thickness. No other locality has given us such an 

 astonishing insight not only into the life of the Middle Cambrian 

 but as well into what must have been the stage and diversity of 

 invertebrate life in pre-Cambrian time. Nevertheless the Burgess 

 shale record is said to be imperfect for "We have only a portion 

 of a crustacean fauna that was already developed early in 

 Cambrian time" (153). 



Students of trilobites will be much interested to know that 

 these animals (certainly at least Neolenus) had a pair of long- 

 jointed caudal rami that are not unlike those in Apus. On the 

 other hand Marrella is a trilobite suggesting Apus in its long and 

 tapering abdomen. 



Walcott states that these Middle Cambrian Branchiopoda and 

 Malacostraca have normally 6 pairs of cephalic appendages, if the 



