Geology and Mineralogy. 221 



the great scarcity of such swamp forms as Sigillaria and Lepido- 

 dendron, of which no recognizable species has been determined. 

 This monograph is a beginning toward a satisfactory determina- 

 tion of the Coal Measures of eastern Canada, and their correla- 

 tion with equivalent strata in the rest of the world. c. s. 



2. Pre- Cambrian Algonkian Algal Flora ; by Charles D. 

 Walcott. Smithson. Misc. Coll., vol. lxiv, No. 2, pp. 77-156, 

 pis. 4-23, 1914. — In this paper are described and well illustrated 

 eight new genera (JVeiclandia, Camasia, Weedia, Collenia, Grey- 

 sonia, Copperia, Fumeyia, and Gallatinia) and fourteen new 

 species of calcareous deposits formed by plants allied to the blue- 

 green alga3 (Cyanophyceae). Although the fossils are from the 

 Belt series (Upper Proterozoic) of Montana, they have been stud- 

 ied in connection with living forms. Similar fossils have long 

 been noted by Walcott at various localities as Cryptozoons, but 

 it was only recently that he obtained material revealing their 

 internal structure. It is now apparent that these organic deposits 

 are far more abundant and of greater chronologic importance 

 than was formerly known ; a wide field of endeavor is thus 

 opened up. 



The author holds that these fossils were formed in " non- 

 marine bodies of water " and that " the Algonkian period in 

 North America with its great epicontinental formations was a 

 time of continental elevation and largely terrigenous [= conti- 

 nental] sedimentation." In other words, that the known deposits 

 yielding fossils are of freshwater origin and were laid down in 

 lakes comparable to the Great Lakes. He says further, " A great 

 work of the future will be the finding of marine deposits of 

 Algonkian time and their contained life." The reviewer does 

 not subscribe to these views and holds that the rocks with these 

 algal formations were formed like those of the Ordovician with 

 Cryptozoon, and that they are of marine origin ; but why the 

 ancestors of the Cambrian animals fail to be present in the Pro- 

 terozoic strata still remains unanswered. The thick limestones of 

 the Proterozoic (Newland, 2000 feet), but more especially of 

 the Archeozoic (the Grenville series has a thickness of 50,000 feet 

 of limestones), are seemingly not the deposits of freshwater lakes 

 but of shallow and warm- water seas. All known freshwater 

 limestones are thin deposits and limited in area, while those of 

 the Algonkian have the physical characteristics of the marine 

 limestones of the Paleozoic. 



Walcott's paper once more raises the long discussed questions : 

 Is Eozoon canadense Dawson of the Archeozoic (Grenville) an 

 organism ? Are these objects to be regarded as highly meta- 

 morphosed Cryptozoons? These masses, alone, as seen in muse- 

 ums, cannot answer the questions, but their field relations compared 

 with those of the Belt and Ordovician strata may give a decisive 

 answer and an organic vista into the supposedly unfossiliferous 

 Archeozoic era. c. s. 



3. On the Petrology of the Orijarvi Region in Southwestern 

 Finland; by P. Eskola. Bull. d. Comm. Geol. de Finlande, 



