

CONTENTS 



Page 

 Art. XXVII.— The Middle Ordovician of Central and South 



Central Pennsylvania; by R. M. Field 403 



Art. XXVIII. — Note on an Unusual Method of Rounding of 



Pebbles in sub-arid Western Australia ; by J. T. Jutson 429 



Art. XXIX. — Sheet-flows, or Sheet-floods, and their asso- 

 ciated phenomena in the Niagara District of sub-arid 

 south-central Western Australia; by J. T. Jutso^" 435 



Art. XXX. — Cacoclasite from Wakefield, Quebec; byN. L. 



Bowen 440 



Art. XXXI. — An Interesting Occurrence of Manganese Min- 

 erals near San Jose, Californi ; by A. F. Rogers 443 



Art. XXXII. — Orthogenetic Development of the Costae in 



the Perisphinctinse; by Marjorie O'Connell, Ph.D.. . 450 



Art. XXXIII.— Heterolasma foerstei, a New Genus and 

 Species of Tetracoralla from the Niagaran of Michigan ; 

 by G. M. Ehlers 461 



SCIENTIFIC INTELLIGENCE. 



Chemistry and Physics — Determination of Zirconium by the Phosphate Method, 

 G. E. F. Lundell and H. B. Knowles, 467. — An Introductory Course in 

 Quantitative Chemical Analysis, G'. McP. Smith, 468. — Richter's Organic 

 Chemistry, P. E. Spielmann : Notes on Qualitative Analysis, L. A. Test 

 and H. M. .V cLaughlin, 469. — The Chemistry and Manufacture of Hydro- 

 gen, P. L. Teed : Calculation of the Radiation Constants c 2 and <r, F. Hen- 

 ning, 470. — Indices of Refraction for X-Rays, A. Einstein, 471. — The 

 General Polarization Surface, F. Jentzsch-Grafe, 472. — Aviation, B. M. 

 Carmina : Molecular Physics, Second Edition, J. A. Crowther, 473. 



Geology and Natural History — Western. Australia Geological Survey, T. 

 Blatchford, etc. : New Zealand Institute Science Congress, Christchurch, 

 1919, 474. — Descriptions and Revisions of the Cretaceous and Tertiary 

 Fish-Remains of New Zealand, F. Chapman : The Prickly Pear in Austra- 

 lia, W. B. Alexander, 475. — United States Geological Survey, G. O. 

 Smith, 476. — Foliation and Metamorphism in Rocks, T. G. Bonney ; 

 Observations on Living Lamellibrancns of New England, E. 6S. Morse : 

 Elementary Biology ; An Introduction to the Science of Life, B. C. Gruen- 

 berg, 477. 



Miscellaneous Scientific Intelligence —National Academy of Sciences, 478. 



Obituary— J. W. H. Trail : C. G. Hopkins : C. H. Hitchcock, 478. 



Index, 479. , 





