1038 General Notes. 7 [October, 
GEOLOGICAL Notes, — General—The age of the formations 
around Keff, in Tunis, has been determined by M. Maris by the 
aid of the fossils. There is a regular superposition of upper crè 
taceous, eocene and miocene. The middle eocene, or nummuliti 
beds, rest directly upon the Senonian or chalk, without the inter 
position of.a lower eocene. The uppermost part of the cretacs 
ous is very rich in fossils, especially in small echini related to 
Faujasia, and may belong to the Darian stage. The most inter 
esting of the lower beds are those which enclose Heterocerus pol 
plocum, and correspond to the upper Senonian beds of Tercis, ia | 
Westphalia, and to the chalk of Meddon. 
Lertiary.—M. Dieulafait’s conclusions regarding the origin ol 
the phosphorites and ferruginous clays of France are as follows: : 
(1) The quantity of phosphate of lime existing in the cavems 
of the south-west of France does not represent a tenth part of 
that which existed in the limestones, the removal of which pro- 
‘duced the caverns. , a 
(2) The ferruginous clays, which accompany and often cover 
the phosphates, have the same composition as those which are 
obtained by attacking with a feeble oxydating acid, the rocks cot | 
stituting the walls of the phosphorite caverns. 1 
3) Tar substances, sk $ manganese, nickel, cobalt, zing, l 
copper, and iodine, which exist in the normal rocks of he 
phorite districts, are found in a relative state = concentration 1t 
the phosphorites and in their accompanying clays. a 
These results point to the possibility that the phosphorites 
the calcareous plateaux of the south-west of France have, lor 
most part, if not entirely, been extracted from the eiaa “x 
solely by the influence of the chemical reactions of 
method. 
MINERALOGY:! a g 
ALLANITE, APATITE AND TYSONITE Crysrars— Profes ne 
ue 
Dana? has given careful crystall hic descriptions 
of given carefu crys ograp: > a tyso 
pe y 
The apatite crystal, of a deep blue color, was small (%4 ted by 
+ Edited by Professor H, CarviLL Lewts, Academy of Nee Be sent 
delphia, to whom munications, papers for review, etc., sho 
"Amer. Fourn. Sc., 1884. 
