184 The American Geologise. September, is96 
of Cretaceous fossils in the lowest layer of the Eocene. A similar case 
of redeposited Cretaceous fossiJH in the Eocene has been recorded from 
the neighborhood of Wilmington, N. C. but the exact horizons involved 
were not determined with sufficient accuracy to permit its use as evi- 
dence of a general non-conformity. The complete change in the marine 
invertebrate fauna, in passing from the latest Cretaceous to the Eocene, 
which is only emjjhasized by the present work in which every known 
species from the lowest Eocene etage is figured, has long caused pal- 
eontologists to believe that there could not have been continuous depo- 
sition from the one to the other, but the horizontal position and 
similarity of the beds has made the recognition of the stratigraphic 
break difficult, es{)ecially when, as at I'rairie Bluff, Alabama. 100 feet 
of the Eocene has usually been assigned to the Cretaceous and the con- 
tact has consequently been sought at the wrong horizon. 
No exact correlation is attempted with the Eocene of Europe, though 
the author states that there is a general similarity of faunas, usually 
without specific identity, in the basal Eocene of the two regions. The 
Midway favina is more closely related to the fauna of Maria Farina, 
Brazil, which was described as Cretaceous, but is referred to the Eocene 
bv professor Harris. Whether the Brazilian fossils are Eocene or not, 
the fauna of about 140 mollupcan species described and figured in the 
body of this work are unquestionably Eocene and show but slight re- 
lationship with our latest Cretaceous fauna. So far as known they have 
not a single species in common. 
Lack of space forbids a detailed review of the biological features of 
the Midway fauna. Of special interest are the first record of tjie oc- 
currence of Reilostoma and Perna in the American Eocene, and the 
extension of the range of the Navitiloid genus Enelimatoceres through 
the whole thickness of the Midway beds. The reviewer has collected a 
similar species of Perna in the lowest Eocene beds of California. 
Three other important papers, by Prof. Harris and Mr. T. H. Aldrich, 
on Tertiary faunas have already appeared in this series of bulletins and 
the gratifying announcement is made that the present monograph is to 
be followed by similar ones on the other Eocene faunas. 
Attention should be called to the omission of an index, which in a 
work of this kind, treating so many species, is a serious matter to the 
busy worker. It is doubtless the intention to index the whole volume 
of which this forms a part, but such large paleontological papers, com- 
plete in themselves, should be indexed independently. For similar rea- 
sons, as well as to improve the appearance of the page, it would be 
better to use a greater variety of type in the descriptions of the species, 
especially in the headings. t. w. s. 
The Fauna of the Magnesian Series. F. W. Sardeson. (Bull. Minn. 
Acad. Nat. Sci., vol. iv, no. 1, pp. 92-105, plates 5 and 6, 1896.) This 
paper consists chiefly of a succession of very brief notes and descriptions 
of twenty-nine species (two trilobites, five brachiopoda, seventeen gastro- 
poda and five cephalopoda — eighteen of them new) which have been ob- 
