Geology and Mineralogy. 487 
12. Measurements of Gravity at Initial Stations in Americ 
a 
and ant 145 PP 4to. Shenae a Se, 1879. (U. S. Coast Sur- 
gather of gravity at initial stations in America and Europe. 
It includes the discussion of the observations made with a Bessel 
Frervible pendulum and of the large number of corrections re- 
quired in obtaining the true result. The observations were 
obtained with the same pendulum, swung at the following sta- 
wa ih Geneva, Paris, Berlin, Kew and Hoboken. By this 
means the observations in America are connected immediately 
with. elise of the most important prakve abroad, where the chief 
absolute determinations have be = cyaee and from which pendu- 
lum expeditions have been sen The station at Hoboken 
thus becomes the initial station for aes continent. Similar action 
already swu m 
Berlin; this is in compliance with the plan adopted at the meet- 
ing of the International Geodetic Congress in Paris in 1875. 
IL. GEoLoGy AND MINERALOGY. 
1. Geological Survey of Pennsylvania. The Permian 
Upper Carboniferous Flora of West Vir. Mond gn Southbod 
Pennsylvania ; by Wu. A, FonTarne, Prof. I. Univ. of Vir- 
ginia, and LC. Wurrn, Professor Nat. His “Univ, West Vir- 
ginia and Assistant Geologist on the Genlogiea Survey of Penn- 
sylvania, 144 pp. 8vo, with 38 plates——The authors derive, from 
the study. of the plants of the “ Upper area" ‘Coal Measures of 
Pennsylvania and Virginia, that this part of the sty a Carbon- 
iferous formation, is ah ecipuas in its relations. ae ecies deter- 
ee re Mees Caltipteridiam, rte is, oniopteri Cynon: 
glossa, Alethopteris, Taniopteris, Rhac cont Cauli eris, 
Sigillaria (two apeueth Cordaites, ep tear , Carpolithes, 
Permian uae which the edhe present. Out of 107 
sie found in the Upper Barrens of West Virginia, 22 occur 
in the Coal Measures proper, while 28 Gr 16 of the pre- 
ceding 22) are pales ge Permian ae a 12 have 
two, Caltipteris ei 8 a and Aletho, opteris gigas, are exclusively 
Permian. Again, 0 ne obtusiloba is a characteristic Per- 
mian pipers The genus Baiera, which first appears abroad in 
the Permian, has a s sete B. Vir rginiana, differing chiefly in 
greater size and robustness from the Permian B. digitata. There 
are no Lepidodendra, Alethopterids and etl ape gece are rare 
(two of the former and four of the latter); nearly a all the Peeop- 
terids have the arborescent character which sherabevises Permian 
