CONTENTS. Vll 



Number 251. 



Page 

 Art. XXXVIII. — The Aneestry of Insects with particular 

 references to Chilopods and Trilobites ; by J. D. 

 Tothill... - 373 



XXXIX. — Some Characters of the Apical End of Pseudor- 

 thoceras knoxense McChesney; by G. H. Girty (With 

 Plate I) - -- 387 



XL. — On the Electrolysis and Purification of Gallium ; by 



H. S. Uhler and Philip E. Browning 389 



XLI. — A Pleistocene Locality on Mt. Desert Island, Maine ; 



by D. Blaney and F. B. Loomis 399 



XLII. — Methods in Reversed and Non-reversed Spectrum 



Interferometry; by C. Barfs 402 



XLIII. — A Study of the Separation of Hydrofluoric Acid 



and Fluosilicic Acid ; by J. G. Dinwiddie 421 



SCIENTIFIC INTELLIGENCE. 



Chemistry and Physics— Occurrence of Germanium in Zinc Materials, G. H. 

 Buchanan, 430. — New Volumetric Method for Cobalt, W. D. Engle and 

 R. G. Gustavson, 431. — Determination of Aluminium as Oxide, W. Blum: 

 Ozone, its Manufacture, Properties, and Uses, A. Vosmaeb, 432. — A 

 Theory of Color Vision, R. A. Houstoun, 433. — On the Auditory Sense, M. 

 Marage, 435. — Concise Technical Physics, J. L. Arnold, 43b. — A Text- 

 Book of Physics, Fourth Edition, A. W. Duff, 437. 



Geology — Expedition to the Baltic provinces of Eussia and Scandinavia, 

 1914, P. E. Raymond and W. H. Twenhofel, 437. — Upper Ordovician 

 formations in Ontario and Quebec, A. F. Foerste: Lower Eocene floras of 

 Southeastern North America, E. W. Berry, 438. — Some Permian Brachio- 

 poda of Armenia, A. Stowanow: Cambrian Geology and Paleontology, 

 iii, No. 5, Cambrian Trilobites, C. D. Walcott : Checklist of the Recent 

 Bivalve Mollusks (Pelecypoda) of the Northwest Coast of America, W. H. 

 Dall : Interrelations of the Fossil Fuels, J. J. Stevenson, 439. — The 

 Echiaoidea of the Buda limestones, F. L. Whitney : Publications of 

 the United States Geological Survey, G. O. Smith, 440. 



Miscellaneous Scientific Intelligence- — Diseases of Occupation and Vocational 

 Hygiene, G. M. Kober and W. C. Hanson: Problems of Physiological and 

 Pathological Chemistry of Metabolism (von Furth), A. J. Smith, 442. 



