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DIRECTIONS FOR STUDENTS. 
This text-book embraces not only a system of 
io be used for ascertaining the names of animals; 
but also the most important elementary principles 
of the science of Zoology, given in a concise fami- 
liar manner. 
The student should commence at page 7 and 
study the whole attentively to the middle of page 
4i, ‘Then read the remarks on pages 53, 62, 76, 
79, 91, 94, 96, 98, 111, 1418, 120, 128, 125 and 
129. Also the directions on pages 133, 134 and 
435. Also the sections and remarks upon the spe- 
cies, under the generic names Silpha, p. 253, and 
Vespa, p. 275. 
Several species of American fresh-water shells 
are described for the purpose of exercising students 
in the study of shells; chiefiy from Say and Barnes, 
most of which they propose as new. More might 
have been copied from Say, in Long’s Expedition. 
But Lthink that most of these new species require 
reviewing. On comparing the characters with 
descriptions of European species, I should be in- 
clined to recommend an exchange of specimens 
with European naturalists, before they are offered. 
as new, and in some cases a comparison of the 
proposed new species with each other, especially 
some of the new species of Mya, of the section 
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