96 
REVIEWS. 
is not the length and minuteness of the original descriptions of new species 
that is likely to crush the literature of Entomology under its own weight; 
but, on the contrary, the brevity and the omissions which give occasion to 
fresh descriptions of the species, no more satisfactory than the first, to 
consequent critical doubts, clashing opinions, and prolix discussions arising 
out of them. And the uncertainty in which the beginner is left, in 
attempting to determine the species he possesses, discourages him, and 
often leads to his giving up collecting altogether. There is no other 
order of insects which labours under these disadvantages to the same 
degree as the Diptera. The reason lies in the multiplicity of the species, 
the minuteness of the distinctive characters in. many of the families, the 
want of sharpness in the outlines, owing to their soft consistency, and the 
general absence of sculpture. Their liability, also, to injury in the act of 
capture, and the difficulty attending their preservation in the cabinet subse¬ 
quently, are not without a concurrent influence. For all these reasons, 
the greatest circumspection is advisable in promulgating new species of 
Diptera. We would not have it supposed for a moment that we think of im¬ 
plicating Mr. Walker in the levity of authors like R. Desvoidy, for instance, 
whose extravagant book, Les Myodaires, stands as a stumbling-block in 
the way of the science, to get rid of which may task for many a long year 
the efforts of the ablest entomologists, which might have been employed to 
much better purpose. But Mr. Walker is too experienced an entomologist 
to feel persuaded himself that such descriptions as he has given of many 
species of Tachina and Anthomyia are calculated to meet the exigencies 
of science. And those descriptions of new species, or what are taken for 
such, have robbed him of . the space requisite to give a complete list and 
the distinctive characters of the previously-described species which are un¬ 
questionably indigenous, and have obliged him to dispose of the con¬ 
fessedly difficult discrimination of the species of these genera in a very 
superficial manner. But it is not only that his work has lost more, as a 
Fauna, than science in general has gained, by his introducing those de¬ 
scriptions ; but we must object, on principle, to the publication of new 
species as part of the Fauna of any European country. Since every work 
of this nature must soon become obsolete, by reason of the more perfect 
investigation of the district, everything should be excluded that bears a 
different and a durable character. Nor can any Fauna afford the room 
necessary to characterize the new species with sufficient minuteness. It is 
in vain to appeal to such an instance as Zetterstedt’s work on the Diptera 
of Sweden. That is the fruit of along lifetime exclusively devoted to the 
