794 
The American Xaturalist. 
The illustrations are, with a few exceptions, well executed, but the 
paper on which they are printed is poor. To this may be excepted 
two lithographs which close the series. The subject is not, however, 
so fully illustrated as its scope demands, as there should be plates of 
the principal features of every genus. This we do not find, although 
some of the genera, as Amblystoma, Hyla, Bufo, and Rana, may be ex- 
cepted from this criticism. An especially valuable feature of the work 
to American students is the illustration of the osteology of genera exotic 
to North America. This feature, together with the exhaustive character 
of the systematic analysis, renders the book a manual of the class at large. 
Frequent reference to the habits of the species is made. We make 
the following extracts descriptive of the ways of these often abundant 
denizens of our forests and swamps. Of the Amblystoma tigrinum, 
Prof. Cope remarks (p. 83) : 
" The larvae of this species are exceedingly abundant in all still 
water in the Rocky Mountain region and the plains. They are 
rapacious, eating animal food, and taking the hook readily. Late m 
the summer they complete their metamorphoses and take to the land, 
where they hide in the holes of marmots, badgers, etc. From these 
they emerge during and after rains. The larvae are much less fre- 
(luently seen in the East, where the species is less abundant, and the 
opportunities of concealment are greater. Market Lake is a temporary 
body of water covering many square miles in Eastern Idaho. It is 
formed by the overflow of the Snake River in Spring. On its shores 
I have found this species. On the shore of an adjacent pond of more 
permanent character I have observed this species occupying vertical 
holes, which were kept filled with water by occasional waves, but from 
which their heads emerged into the air. In this position their branchiae 
were gradually absorbed. An adult from New Jersey occupied a 
burrow in the soil of my fernery for several weeks. The burrow had 
two orifices, in one or the other of which its head could be generally 
seen, observing what was going on." 
The larva of Chondrotiis tenebrosus is thus described : 
" The larva of this species frequently exceeds in dimensions that of 
any other species, and quite equals the adult. It is a uniform lead 
color, or sometimes blackish, and the muzzle is rather abruptly short- 
ened. The tail has a fin at its extremity, which extends also well 
anteriorly on the superior edge. The digits are flattened, and their 
apices are protected in many specimens by a horny cap of a blackish 
color. This larva, however, differs from that of other sj^ecies of the 
genus in other characters of more importance. First. There are no 
