Review of Recent Geological Literature. 183 
gradually depressed, and the country becomes rougher until max- 
imum are reached. Then follows a reduction of the inequalities cf 
the surface, and finally in old age, the smooth, gently rounded outlines 
of geographic infancy appear again. So in organisms, the smooth, 
rounded embryo or larval form progressively acquires more and more 
pronounced and highly differentiated characters through youth and 
maturity. In old age it blossoms out with a galaxy of spines, and 
with further decadence produces extravagant vagaries of spines, but 
in extreme senility comes the second childhood, with its simple growth 
and its last feeble infantile exhibit of vital power. 
“The history of a group of animals is the same. The first species 
are small and unornamented. They increase in size, complexity and 
diversity until the culmination, when most of the spinose forms be- 
gin to appear. During the decline extravagant types are apt to de- 
velop, and if the end is not then reached the group is continued in the 
small and unspecialized species which did not partake of the general 
tendency to spinous growth.” 
Scarcely less important are the author’s various papers on the 
structure and development of trilobites, though less unique. He here 
states the principles of a natural classification of trilobites, discusses 
their systematic position, entering more minutely into the morphology 
of Triarthrus and the structure and appendages of Trinucleus. 
The body of the volume closes with papers on the development of 
a poriferous coral, a symmetrical cell development in the Favositidae 
and on the shell of Tornoceras Hyatt. 
This gathering together of the papers of Dr. Beecher in a symmet- 
rical body constitutes a notable contribution to evolution, and every 
geologist will rejoice that they are brought into this convenient and 
compact form accompanied, as they are, by such emendations as 
bring them up to date. N. H. W. 
MONTHLY AUTHOR’S CATALOGUE 
OF AMERICAN GEOLOGICAL LITERATURE 
ARRANGED ALPHABETICALLY, 
BARBOUR, E. H. 
Report of the Geologist; altitudes in Nebraska. (Ann. Rep. Bd. 
Agr., 1900, pp. 169-180.) 
BARBOUR, E. H. : 
The state geological survey [Nebraska]: report of progress for 
the summer of 1900. (Proc. Neb. Acad. Sci., vol. 7, 1901, pp. 166-169.) 
BARBOUR, E. H. 
The unpublished meteorites of Nebraska. (Proc. Neb. Acad. Sel., 
vol. 7, p. 34, pl. 1, 1901.) 
