Beviev) of Recent Geological Literature. ](iO 
took place. Why have not the remainH of Cretaceous raaminals been 
discovered? It is not enough to say that all the Cretaceous deposits 
accessible to geologists were laid down in the open sea in situations 
where manimalian remains were not likely to be carried. Such a state- 
ment is no longer true. The Dakota group with its leaves of phfeno- 
gamouB forests in the lower horizon of the Cretaceous of the Upper 
Missouri, and the Laramie group at the do.so of the period, were 
laid down under circumstanct's in all respects favoral>le for receiving 
and preserving mammalian remains. Moreover the skeletons of Dlno- 
aauria, which were as terrestrial in habit as ordinary mammals, are 
represented in Cretaceous strata by abuntlant and well i)reserved 
specimens. The Zeuglodon did not acquire its adaptation to marine 
life suddenly. It must have had aquatic predecessors whose remains 
are entombed somewJiere in strata of the later Cretaceous. 
As professor Marsh well says: "A comparison of mammals known 
from the Jurassic and Tertiary made it almost certain [we would 
say quite certain] that many intermediate forms must exist in the Cre- 
taceous, and their discovery was one of the prizes held out to explor- 
ers." 
The paper before us marks an important epoch in our knowledge of 
the history of mammalian life. It contains tlie first intimation we have 
had of it rinding of unquestioned mammalian remains in strata of Cre- 
taceous age. The finding of such remains is so far confined to the 
Laramine group, a group by the way that has by excellent geologists, 
been referred to the lower Tertiary, although its relations to the Creta- 
ceous will now be generally acknowledged. A long breach in mam- 
malian history still remains to be filled, ])ut now that an entrance into 
this long sealed portion of the mammalian record lias been secured we 
may hope that discoveries will follow eacli other in <juick succession. 
The mammalian remains described by professor Marsli w^re found 
by Mr. J. B. Hatcher in Wyoming and Dakota, and were associated 
with Iladrosaurtis and other Dinosnuria. They are not exactly what 
we might reasonably expect the mammals of the Laramie group to be, 
for they are all rather small creatures, 'more nearly related to the mam- 
malian fauna of the Jurassic than of the Tertiary; most are marsupials 
but some have structures indicating relationship with monotremes, a 
fact of great interest and significance. Seventeen species are noted, 
and these, together with others from the same horizon, will be fully de- 
scribed an<l figured in a memoir on mesozoic mammals, now in process 
of preparation, and to be published by the United States geological 
survey. Four plates illustrate the article here under consideration. 
The Invertebrate Fauna of the Ilawkrsbnry-Wiiniarnatla Series of Xew 
SotUh Wales. By Uobert Ethekiogk, Jr. This quarto publication 
embracing 21 pages and one plate is the first of the palwontological 
memoirs of the geological survey of New South Wales. S. C. Wilkin- 
son, F. G. S., tfcc, is the geological surveyor-in-charge. 
The series of rocks here named the Hawkesbury-Wianamatta series 
