334 The American Geologist. November, 1894 
any subsequent time exceeded them in these respects. The predomi- 
nant types, Lep.erditiida) and Beyrichiida, moreover, after holding their 
own perhaps through the Upper Silurian, were greatly reduced during 
Devonian and Carboniferous times and are now totally extinct. Some 
recent families and genera, on the other hand, are sparingly represented, 
hut, taken as a whole, the Silurian OstraCOda fauna is decidedly pe- 
culiar. 
"TheOstracoda are every where poorly represented in the Triassic and 
Jurassic. But in the Cretaceous and Tertiary strata of Europe certain 
genera, Gythere especially, develop an astounding variety and wealth of 
species. The forms are all small, and this may in part account for the 
fact that so few have been discovered in American deposits of these 
ages. " g. s. 
EUmenU de Paleontologie. Par Felix Bernard; seconde partie (pp. 529- 
1,168) avec ?31 figures dans le texte. Paris. Bailliere et flls, 1895. The 
reader is referred to vol. xi, p. 410, American Geologist, for a notice of 
the first part of this work. With this part the volume is closed. Al- 
though it is especially addressed to French scientists, in whose litera- 
ture if certainly must constitute a valuable contribution to the philos- 
ophy of paleontology, it will be closely scanned by many in other 
countries who may be seeking for a concise presentation of the evolu- 
tionary steps and the structural relations through which life upon the 
globe has passed to its present stages. The author's chief aim is to 
exemplify the relations of paleontology to the biological sciences, rather 
than to set forth the special characters of numerous species or genera. 
He dwells, therefore, on the morphology and the internal structures and 
on the embryoldgical development of fossil forms. The march of life, 
therefore, as presented is a- grand panorama of evolution. The work 
covers both animal and vegetable paleontology. It is specially full in 
the discussion of the mammifers and reptiles, and many American dis- 
coveries in the development of these classes, are credited to Cope and 
Marsh. With this exception recent American paleontological work is 
not so fully recognized. N. H. w. 
Principe8 et Methodes d'itudede Gorrdlation nu moyen desPlantes Fossiles. 
By Lester F. Ward. Congres Geologique International, Compte Rendu 
de la 5me Session, Washington, 1891 (published 1893), pp. 77-109. This 
paper admits fully the view propounded by Huxley that the successive 
floras of different regions should be regarded as homotaxial rather than 
contemporaneous, that is to say, their contemporaneity should be meas- 
ured rather b\ their general aspect than by strict identity of species. 
Following this principle, Prof. Ward lays down, as rules of practice in 
paleobotany, (1) that any striking deviation from homotaxis implies a 
wide difference of date, quoting the discovery of a few Carboniferous 
fossils in strata from the High Alps supposed by de Beaumont, in 1828, 
to be of Mesozoic age, as absolutely conclusive: and (2) that stronger ev- 
idence is needed when the difference of age is much less, as in the case 
of the Gay Head strata, pronounced by Shaler to be of Tertiary date, 
