Geology and Natural History. 77 



pre-Cambrian. On the colored geological map accompanying the 

 paper, the Cambrian is made to pass south and southwest over 

 Falls Village into Rhode Island. The rocks of the Cambrian 

 are shales and conglomerates. The Cambrian area of Brain tree, 

 where the Paradoxides Harlani occurs, is twenty-five miles to 

 the north ; but it was not possible to make out the stratigraphic 

 relations between the two. The fossils discovered are: Obolella 

 crassa Hall, Fordilla Troyensis f, Scenella reticulata Billings, 

 Stenotheca rugosa, Stenotheca curvirostra, sp. n., Platyceras pri- 

 maivum Billings, Pleurotomaria (Paphistoma) Attleborensis, sp. 

 n., Hyolithes qiiadricostatus, sp. n., PL. communis var. Emmonsi 

 Ford, H. Americanus Billings, H. princeps Billings, H. Billingsi 

 Walcott?, Hyalithellus micans Billings, Salterella curvatus, sp. n., 

 Aristozoef, Microdiscus bellimarginatus, sp. n., M. lobatus H., 

 Paradoxides Walcotti, sp. n., Ptychoparia mucronata, sp. n., 

 P. Attleborensis, sp. n. The fossils are figured on two plates. 

 In the study of the fossils, Professor Shaler was aided by Mr. 

 A. F. Foerste. The authors remark that while the fossils are 

 those of the " Olenellus group," the beds contain no species of 

 Olenellus, and that the presence of a Paradoxides "diminishes 

 the importance of the Paradoxides division of the Cambrian." 

 The species of Paradoxides is very small, or the specimen is 

 young. 



2. Silicified wood of Arizona ; by F. H. Knowlton. — A large 

 trunk of silicified wood from the vicinity of Fort Wingate, Ari- 

 zona, which has been on exhibition for several years at the II. S. 

 National Museum, Washington, has been studied by Mr. Knowl- 

 ton, and named (Proc. U. S. Nat. Mus., 1888, p. 1) Araucari- 

 oxylon Arizonicum. A plate (Plate I) accompanies the paper. 

 Mr. Knowlton also describes two new species of fossil conifer- 

 ous wood from Iowa and Montana, which he refers to the ge- 

 nus Cressinoxylon (Plates II, III). 



3. Dahllite, a new mineral— Brogger and Backstrom have 

 described a new mineral from the apatite region in the parish of 

 Bamle, Norway. It occurs as a rather thin crust, which has a 

 rounded lustrous surface and a fibrous structure, the fibers being 

 perpendicular to the base of massive reddish apatite. The color 

 is pale yellowish white or reddish yellow, but appears colorless in 

 a thin section ; it is translucent and somewhat resembles chalce- 

 dony. It is optically negative. The hardness is about 5 and 

 the specific gravity 3-053. An analysis gave the following results: 



P 2 5 



CO a 



CaO 



FeO 



Na 2 



K 2 



H 2 



38-44 



6-29 



53-00 



0-79 



0-89 



0-11 



1-37 



100-89. 



This corresponds essentially to the formula 4Ca 3 P 2 8 + 2CaC0 9 + 

 H 2 0. The microscopic and chemical examination convinced the 

 authors that the mineral was homogeneous, notwithstanding its re- 

 markable composition. — (Efv. Vet-Akad. Forhandl, p. 493, 1888. 

 4. Pas Protoplasma als Ftrmentorganismus / von Prolessor 

 Dr. Albert Wigand. Marburg, 1888, pp. 294. — Few scientific 



