YOL. XXIY. 



^0 ST. q 3 



OCTOBER, 1907. 



Established by BENJAMIN SILLIMAN in 1818. 



THE 



AMERICAN 



JOURNAL OF SCIENCE. 



Editor: EDWAED S. DANA. 



ASSOCIATE EDITORS 



Professors GEOEGE L. GOODALE, JOHN TEOWBEIDGE, 

 , W. G. FAELOW and WM. M. DAVIS, op Cambridge, 



Professors ADDISON E. VEEEILL, HOEACE L. WELLS, 

 L. V. PIESSON and H. E. GEEGOEY, of New Haven, 



Professor GEOEGE E. BAEKEE, of Philadelphia, 

 Professor HENEY S. WILLIAMS, of Ithaca, 

 Professor JOSEPH S. AMES, of Baltimore, 

 Mr. J. S. DILLEE, of Washington. 



FOURTH SERIES 



YOL. XXIY— [WHOLE NUMBER, CLXXIY.] 



No. 142— OCTOBER, 1907. 



WITH PLATES I, II. 



NEW HAVEN, CONNECTICUT. 

 1907 



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