The price of this Journal to the General Public is as marked on the 

 front page. Every member of the Association is supplied with one copy 

 frec.^ and may obtain extra copies at half-price. Applications for copies 

 should be addressed to the Assistant General Secretary, P.O. Box 6894, 

 Johannesburg. 



CORRESPONDENCE.— All communications other tihan those 

 relating to the Journal should be addressed to the Assistant Secretary, P.O. 

 Box 6894, Johannesburg. (Telegraphic address: "Science," Johannesburg.) 



Communications for the Editor should be addressed to P.O. Box 

 1 176, Johannesburg- 



REPRINTS. —Authors desiring to have reprints of their papers, read 

 at the Annual Meeting of the Association, are requested to notify the 

 PMitor, as to the number required, when returning their proofs. 



ILLUSTRATIONS (other than photographs) accompanying papers 

 intended for publication in the Journal must be supplied by the authors, 

 carefully drawn about TWICE THE SIZE of the finished block, on smooth 

 white Bristol Board in INDIAN INK, so as to admit of the blocks being 

 prepared directly from the drawings. Any lettering on these drawings 

 should be of such a size that it will be clearly legible when reduced. 



LOOSE COVER CASES.— Cases uniform in all respects with the 

 covers of previous volumes, may be obtained for binding Vols, vi (1909) 

 to XV (1918), on application to the Assistant General Secretary, at a cost 

 of IS. per case, and sixpence for postage. 



SUBSCRIPTIONS.— Subscriptions of J^l for the year ending 

 30th June, 1920, arc now due. — Members are requested to be so kind 

 as to remit the amount as soon as possible to the Assistant General Secre- 

 tary, P.O. Box 6894, Johannesburg. Unless members pay the amount due 

 at an early date, great inconvenience and unnecessary expense may 

 be caused, as it is very difficult to determine what number of copies of the 

 Journal will be required. The Council therefore appeals to every member 

 for support and co-operation, and asks that outstanding subscriptions be 

 paid without delav. THE JOURNAL WILL BE SENT ONLY TO 

 THOSE WHOSE ARREAR SUBSCRIPTIONS ARE PAID. 



Cheques, etc., should be crossed and made payable to The Association, 

 not to the Secretaries or Treasurer individually. 6d. should be added to 

 country cheques for exdhange. 



CHANGE OF HEADQUARTERS— Attention is called to the 

 change of headquarters decided on at the Kingwilliamstown session. In 

 future the office address of the Association will be " P.O. Box 6894, 

 Johannesburg " ; the telegraphic address will be " Science," Johannesburg," 

 and the telephone number " 5821, Johannesburg." 



Johannesburg, ist July. 1920. 



