Vol. io D]Qcemb^r 19, 1920 No. 21 



JOURNAL 



OP THE 



WASHINGTON ACADEMY 

 OF SCIENCES 



BOARD OF EDITORS 

 J. Franklin Mbtek Robbbt B. Sobican S. P. Blaks 



8DBSAO or aTAllDAXIW OKOPBTKCAL I.ABOSATOKT BDKKAC OV n,AllT tmOOWtWW 



ASSOCIATE EDITORS 



H. V. Bmkum S. a. RoHwnt 



■oTAmcAt. socisTT SMTOMouMKAi, BaeoKn 



N. HoLUSTBR P. B. Sn^BSB ' 



■IOI.OOICAL ■OCtSTT FBIMMOVnCAl, ■ O CUWl 



^DMBT PaIOB J. R. SWANTON ', 



•aoLooiCAi. tocnn AaTamorotootCAt, aecnTv 



PDBUSHBD SSm-lIONTHLT > 



BZCBPT IN JUI.T« AUGUST, AND SBPTBH8BR> WHBN MOMTBLT 



WASHINGTON ACADEMY OP SCIENCES \ 



\ 



orVtCB OV PUBLICATION 



ail CHURCH StKBBT \ 



BA8TON, PA. 



Bntered aa S«c«fid CUm M*tt«r, jAonafy 25. 1919. at tht po*t-«ffle« at Baataa, Pa.; aadat th« 

 Aet of Aagvat 24. 1912. Acceptance far Biafllag at tpceial rata al paataga pravldad f«r is 

 Scetloa 1103 Aet ef Octabet 3, 1917. Aathariaed •■ J«ly i. 1911 



