OBJECTIONS ANSWERED. 25 
You will think it hardly credible that there should be so much difficulty 
in describing an insect intelligibly without the aid of system; but an 
argumentum ad hominem, supported by some other facts, will, I conjecture, 
render this matter more comprehensible. You have doubtless, like every 
one else, in the showery days of summer, felt no little rage at the flies, 
which at such times take the liberty of biting our legs, and contrive to 
make a comfortable meal through the interstices of their silken or cotton 
coverings. Did it, I pray, ever enter into your conception that these blood- 
thirsty tormentors are a different species from those flies which you are 
wont to see extending the lips of their little proboscis to a piece of sugar 
ora drop of wine? I dare say not. But the next time you have sacri- 
ficed one of the former to your just vengeance, catch one of the latter and 
compare them. I question if, after the narrowest comparison, you will 
not still venture a wager that they are the very same species. Yet you 
would most certainly lose your bet. They are not even of the same genus 
— one belonging to the genus Musca (JM. domestica), and the other to the 
genus Stomoxys (S. calcitrans); and on a second examination you will 
find that, however alike in most respects, they differ widely in the shape of 
their proboscis ; that of the Stomoxys being a horny sharp-pointed wea- 
pon, capable of piercing the flesh, while the soft blunt organ of the Musca 
is perfectly incompetent to any such operation. In future, while you no 
longer load the whole race of the house-fly with the execrations which 
properly belong to a quite different tribe, you will cease being surprised 
that an ordinary description should be insufficient to discriminate an in- 
sect. It is to this insufficiency that we must attribute our ignorance of so 
many of the insects mentioned by the older naturalists, previously to the 
systematic improvements of the immortal Linné: and to the same cause 
we must refer the impossibility of determining what species are alluded to 
in the accounts of many modern travellers and agriculturists who have 
been ignorant of Entomology as a science. Instances without number 
of this impossibility might be adduced, but I shall confine myself to 
two. 
One of the greatest pests of Surinam and other low regions in South 
America, is the insect called in the West Indies, where it is also trouble- 
some, the chigoe (Pulew penetrans), a minute species, to the attacks of 
which [ shall again have occasion to advert. This insect is mentioned by 
almost all the writers on the countries where it is found. Not less than 
eight or ten of them have endeavoured to give a full description of it, and 
some of them have even figured it; and yet, strange to say, it was not 
certainly known whether it was a flea (Puler L.), a louse (Pediculus L.), 
or a mite (Acarus L.), till a competent naturalist undertook to investigate 
its history, and in a short paper in the Swedish Transactions’ proved that 
Linné was not mistaken in referring it to the former tribe, with which also 
the more recent investigations of an eminent British entomologist, J. O. 
Westwood, Esq., have shown that it must be arranged, though, from some 
difference in its structure as well as habits, he has adopted the generic name 
(slightly altered) proposed by the Rev. L. Guilding, and has called it 
Sarcopsylla penetrans* 
The second instance of the insufficiency of popular description is even 
_ 1 Swartz in Kongl. Vet. Ac. nya Handl. ix. 40. 
2 Trans, Ent. Soc. Lond, ii, 199—203, 
