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 

 or a 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 (M. 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 Linne : 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 (Pidex penetrans), a minute species, to the attacks of 

 which I 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 (Pulex L.), a louse (Pedlculus L.), 

 or a mite (Acarus L.), till a competent naturalist undertook to investigate 

 its history, and in a short paper in the Swedish Transactions l proved that 

 Linne 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 Su-artz in Kongl Vet. Ac. nya Handl. ix. 40. 



2 Trans. Ent. Soc. Lond. ii. li)9 203. 



