YRAKE US 
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MUSEURB TROT HS Vv 
wise, its state is marked! intmediately after the letter by 
which it is distinguished ; and if the sexes are known, it is 
stated to be male or female. These particulars are followed 
by the habitat, which is given as particularly as the mate- 
rials possessed by the Museum permit. Those specimens 
which have been presented to the Museum have the name 
of the donor marked immediately after the habitat. When 
there is no such indication, the specimens have been either 
purchased or procured in exchange ; and in this case, when- 
ever the place or person from whence they have been re- 
ceived gives authenticity to the specimen, or adds anything 
to their history, they are noted as being from such or such 
a collection. . 
The various synonyms have been given to the different 
divisions of the class, and to the genera and subgenera and 
species, and a reference made to the works in which they 
have been characterized or described. 
In the adoption of the names for these divisions and for 
the names of the genera and species, it has been thought 
right to use, whenever it was possible, that which was first 
used for the purpose. As far as regards the specific name, — 
there is comparatively little difficulty in the application of 
this simple rule ; but ordimal, and especially generic names, 
have been used by different authors in senses so widely dif- 
ferent, and the groups which they are intended to designate 
have been so variously extended and restricted, that it is no 
easy matter to determine, where several names have been 
used, which of them ought to be preferred. As every ori- 
ginal observer will constantly make use of characters which 
_ others may ‘have overlooked, or not thought of so much 
importance as further researches have shown to belong to 
it, even when’ a generic name is used, it will of necessity be 
often employed in.a different sense, or with a more restricted 
