Review of Recent Geological Literature. 333 
Illinois reports, for example, would probably exceed in size the nine 
large volumes of that state 
On account of their varying value for classificatory purposes, the 
treatment of the different zoological groups has not been the same In 
order to carry out the main intent of the work, ami still have it included 
within the limits originally planned, it has been necessary to condense 
greatly the consideration of many of the sections. The most character- 
istic forms of the various geological horizons, and the species which are 
little known, have been considered more in detail than other forms 
equally interesting arid perhaps even more important. Certain large 
groups have consecpiently been very briefly alluded to. Such are the 
polyzoans, vertebrates, and various sections of lower taxonomic rank. 
Accompanying the paleontological portion of the report is an intro- 
duction of nearly 100 pages, on the general stratigraphy of the state, 
which contains much new information. 
The illustrations are largely zinc etchings, and for their kind could 
scarcely be excelled. They are works of art, perfectly clear in every 
detail, and entirely free from that "muddiness" which is almost always 
apparent in work of this kind. The drawings were chiefly the work of 
Dr. McConnel, of Washington, D. C, of M. Westergren, who for thirty 
years was draughtsman in the National Museum of Sweden, and of the 
author. n. p. n. 
The Lower Silurian Ostraeodaof Minnesota. By E. O. Ulrich. (Chap- 
ter VII of vol. in. Final Report, Geological and Natural History Survey 
of Minnesota, July, 1894, pp. 029-693, pis. xliii-xlvi.) The crustacean 
order Ostracoda attracts but few paleontologists, although their remains 
appear to be as abundant as the trilobites. This lack of interest is prob- 
ably due to the usually small size of the carapace of these animals, 
though some Silurian and Cambrian species have a length of nearly two 
inches. Geologically younger specimens never attain anything like this 
size. Miller in his "North American Geology and Paleontology, 1889," 
catalogues one hundred and twenty-seven species in eleven genera. In 
3890 Mr. Ulrich described or identified ninety-eight additional species 
and twenty-one genera. In the present work fifty-four species and seven 
genera more are added, making in all about two hundred and eighty- 
live American species of Paleozoic osl racods < I i si ributed in forty genera, 
a growth since 1890 doubling the known species ami nearly quadrupling 
the genera. Collectors will do well to give attention to washing shale 
and Other soft friable strata and thereby obtain many forms of Ostra- 
coda, Bryozoa, and the younger stages of Brachiopoda, Mollusca, Crusta- 
cea, etc. 
[n this chapter are described sixty-eight species, of which lifiy-l'our 
are new. These are grouped under twenty-two genera, of which Leper- 
ditella, Primitidla, Dicranella, DUobeUa, Ceratopsia, Macronotello. and 
Krauxdla are new. 
"In ihr Lower Silurian deposits Ostracoda occur in such great num- 
bers and variety, that it is doubtful if the representation of the order at 
