Geology and Paleontology. 729 
M. Filhol’s restoration showing the long fore limbs and short hind . 
limbs, and feet resting partly on the side, demonstrates that it had 
the habits of the sloths. He also informs me that the older indi- 
viduals retain only one incisor. On the other hand the structure of 
the carpus, tarsus, skull and teeth, is in so many features so strik- 
ingly Perissodactyl, that there seems to be no alternative except to 
leave Chalicotherium in this order and regard it as an aberrant form, 
with nearest affinities to Paleosyops and genera of that line.— 
Henry F. Osborn, Paris, September Ist. 
GEOLOGICAL News.—GENERAL.—Mr. Mellard Reade and Mr. 
Davison have recently pointed out that, owing to the cooling and 
contraction of the earth, there is at some depth beneath the surface 
a zone of no stress, that is to say, where the compressive stress due 
to the radial contraction of the sphere, and the tensile stress due 
to the circumferential contraction of each zone, are equal. Prof. 
C. L. Morgan (Geol, Mag., 1888, p. 296) asks, “Is it not possible 
that throughout the zone of maximum tension, due to circumfer- 
ential contraction, the rocks may be rendered fluid by relief of 
CAMBRIAN AND SILURIAN.—The Paleontological Department 
of the Swedish State Museum has published a list of the Cambrian 
and Lower Silurian faunas of that country, by Prof. G. Lindstrom, 
and another of the Mesozoic fauna, by Prof. B. Lundgren. The 
Cambrian is divided into (1) the Eophyton and Fucoid Sandstones, 
(2) the Paradoxides beds, (3) the Olenus Schists, and (4) the Dic- 
tyonema Slate. One hundred and fourteen species are enumera 
om this formation. The Lower Silurian comprises 1, Ceratopyge 
Limestone ; 2, Lower Graptolite Schists; 3, Orthoceratite Lime- 
stone; 4, Middle Graptolite Schists; 5, Chasmops Limestone; 
6, Trinucleus Schists ; 7, Brachiopod Schists ; 8, Upper Graptolite 
ists; and 9x9, Leptena Limestona. The species enumerated 
from the Lower Silurian number 627. 
CaRBONIFEROUS.—It appears that the peculiar rock called chert 
Consists mainly of the spicules of sponges. Dr. G. J. Hinde has 
found it to be thus composed in the Yoredale series of Yorkshire 
(Eng.), in Wales and in Ireland, while in the June issue of the 
Geological Magazine he describes the character of the sponges of the 
chert and siliceous schists of Spitzbergen. The Permo-Carbonifer- 
