Exchanges 
EXCHANGES 
One of the best ways of adding to a collection is by the method 
known as exchanging. A collector in one part of the country 
may find species which are rare, or altogether unknown, in an¬ 
other part of the country. By a system of exchanges with 
other collectors he is able to supply the gaps which may exist in 
his collection. No one, however, cares to effect exchanges with 
collectors who are careless or slovenly in the preparation of their 
specimens, or inaccurate in naming them. A collector who con¬ 
templates making an exchange should, as the first step, prepare 
double lists, in one of which he gives the names and the number 
of specimens of either sex of the butterflies which he is able to offer 
in exchange; in the other he sets forth the things which he 
desires to obtain. The first list is said to be a list of “offerta 
the second is a list of ‘‘desiderata.” As an illustration of the 
manner in which such lists may be conveniently arranged, I give 
the following: 
OFFERTA 
Papilio turnus, 3> 9 4* 
Dimorphic var. glaucus, 9 6. 
Colias alexandra, cJ' 4> 9 6. 
DESIDERATA 
Papilio nitra, 9* 
Papilio brevicauda, orange-spotted var. 
The collector who receives these lists of offerta and desiderata 
will be able to decide what his correspondent has which he de¬ 
sires, and what there may be in his own collection which the 
correspondent wishes that he can offer in exchange; and the 
process of exchange is thus immediately facilitated. 
Persons who exchange insects with others should always be 
extremely careful as to the manner of packing the specimens, 
and the directions given in the introductory portion of this book 
should be very carefully followed. Too much care cannot be taken 
in preventing damage to specimens in transit. 
Genus ANCYLOXYPHA, Felder 
Butterfly . — Very small, the antennae very short, the club 
straight, bluntly pointed. The palpi have the third joint long, 
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