94 
REVIEWS. 
sider his work to be of more value as a contribution to the classification of 
the indigenous Diptera than as a Fauna. Secondly, .the confessedly im¬ 
perfect knowledge we possess of species has given Mr. Walker occasion to 
expatiate in the descriptions of a vast number of new, or supposed new, 
species. He is not the only author that has written a Fauna on the plan 
of a Phanerogamous Flora, without reflecting on the inherent difference in 
their respective objects* The multitude of species in the class of insects 
is accumulating at such a rate, by constant fresh discoveries, that it has 
become a question which seriously affects the prospects of the progress or 
decline of entomology, in what manner, and through what channels, the 
characters of the new species should be made public. And, as we have 
ventured to find fault with Mr. Walker for introducing so many new spe¬ 
cies into his work, we feel bound to justify the view we have taken, by 
entering a little more at large into this discussion. 
It needs no very profound study of the direction which Entomology has 
been taking, and especially as regards the order Diptera, to convince one 
that the old routine—unhappily not yet quite out of date—can end in 
nothing better than general confusion and error. Antecedent to Fallen, 
Meigen, and Wiedemann, a very few words were thought sufficient to cha¬ 
racterize new species intelligibly for all time to come; while every one now 
who has attempted to identify the species of the older authors knows, by 
experience, what loss of time and labour this requires in most cases. Fal¬ 
len, Meigen, and Wiedemann distinctly saw the error of their predecessors, 
and amplified, accordingly, their own descriptions, in such a measure as 
their experience suggested. We, who are reaping the full benefit of their 
labours, find in turn how often the descriptions even of these admired au¬ 
thors prove insufficient for our satisfaction, from their omitting points which 
would have been decisive. Hence we are brought to the deliberate con¬ 
viction, that in order to authenticate new species, the descriptions of them 
should go into the most minute details ; if the study of the Diptera is not 
to p e — a s threatens to become the case—engulfed in the quicksands of 
endless critical discussion about unsatisfactoiy descriptions, instead of the 
direct observation of nature, and the continually progressive acquisition of 
fresh knowledge. It might have been imagined that the apprehension of 
such consequences "would have served as an effectual check upon the publi¬ 
cation of slight original descriptions : unhappily, experience too plainly 
proves the contrary. The chief reason for this, doubtless, is, that the con¬ 
struction of accurately minute and detailed descriptions is an exercise of 
the most laborious nature. And, as the time and pains required for this 
