Bibliography. 299 
this species was found, measuring, as it lay in its matrix, five feet along 
the range of the teeth, but in such a friable condition, that only a por- 
tion of it could be dislodged ; and this, notwithstanding all the precau- 
tions used in packing and transportation, fell to pieces before reaching 
Indiana.” . ? i: 2 
The author continues with remarks on other Fossil Mammalia from 
this singular region Descriptions of the above and other fossils, in- 
ec 
ag four species of Fossil Turtle, are given in the chapter by Dr. 
itis as old at least as the lowest Silurian. Dr. Owen even suggests 
that it probably underlies the Lingula and Orbicula beds of the Upper 
| 
ted by several hundred magnified representations ; by ANDREW PritcH- 
ARD, M.R.I., &c. . A’new edition, enlarged. London: 1852.—In pre- 
paring the new edition of this useful work, Mr. Pritchard has been 
aided by J. T. Arlidge, and the result of their united labors has been 
the production of a volume containing a large amount of new and in- 
teresting matter in addition to the contents of the preceding edition. 
Without increasing the cost of the work, the number of engravings has 
been doubled, and many additions have been made to the text. Among 
are compilations from Ehrenberg’s numerous papers read before 
the Berlin Academy, including the description of many new genera 
i rk of Ralfs on the Desmidiez has 
y, and from the writings of Kiitsing, Dujardin, Siebold, Stein, 
&e. Ip fact, great industry ou to seat been exerted in collecting 
every thing novel relating to the Infusoria. We must however, express 
our regret that the editors have not devoted more time to the arrange- 
sent and connection of the heterogeneous materials thus assembled. 
lis true that it well represents the present state of this department of 
“lence, in which all is in confusion. But there are parts of the sub- 
Jeet which are no longer doubtful, and we regret that we are presented 
with many erroneous generic and specific characters taken from the 
now obsolete descriptions of Ehrenberg, Kiitsing and others. We al- 
» the surface of various siliceous. shells which may readily be shown 
is lined objects ya iective of even one inch focal distance. 
Pe the decision of these. questions afforded by the action of 
hydrofluoric acid, (see this leon 349,) by means of which it has 
that put beyond all doubt that the apertures have no existence, and 
‘What have borne this name are neither elevations nor depressions 
» but in reality the thickest portion of the shells. As many of 
