

/5 5'o.G^Z-, 



^ K THE 



QUARTERLY JOURNAL 



OF THE 



GEOLOGICAL SOCIETY OF LONDON. 



EDITED RY 



THE PERMANENT SECRETARY OF THE GEOLOGICAL SOCIETY. 



Quod si cui morbalium cordi et curoe sib nou tantum inveutis haerere, aique iis uti, sed ad ulhci-iora 

 penetrare ; atque non disputando adversarium, Med opere naturam vincere ; denique non belle et probabiliter 

 opinari, sed cerfco et ostensive scire ; tales, tanquam veri seientiarum filii, nobis (si videbitur) ae adjungant- 

 — Novum Organuin, Vrafaiio. 



VOLUME THE SEVENTY-SEVENTH, 



FOR 1921. 



LONDON : 

 LONGMANS, GREEN, AND CO. 



PAEIS: CHAELES KLINCKSIECK, 11 EUE DE LILLE. 

 SOLD ALSO AT THE APARTMENTS OF THE SOCIETY, 

 JICMXXI. 



