6178 



Insects 



the shortest alimentary canal in the class of Mammalia ; in obvious 

 reference to aliment so excessively nutritious, being that, indeed, to 

 which all food has first to be converted ! The Megaderma Lyra of this 

 country also sucks the blood of smaller bats, and either devours them 

 afterwards (as I have witnessed of one put into a cage along with its 

 victim), or relinquishes the bloodless carcass : and here we arrive at 

 the predatory animal that absolutely destroys its victim ; as with the 

 Ichneumon flies, &c., which ultimately do the same, invariably, among 

 the true parasitic series. 



According to this view of the matter, however, which seems clear 

 enough, certain vile tiny habitants of the surface, " detested baith by 

 saint and sinner," should belong rather to the predatory class ; but the 

 fact is, there is no drawing an absolute line of distinction : the "Scotch- 

 fiddle" mite (Acarus Scabiei) is sub-cuticular as distinguished from 

 sub-cutaneous ; and other Acari are found inside of the quills of the 

 feathers of living birds; and so the gradations run, till we come to so 

 extraordinary an internal parasite as "the worm in the horse's eye," 

 at which many readers have doubtless gazed in the living quadruped. 

 In other words, thus the Epizoa grade into the Entozoa, untechnically 

 so denominated ; and both fall under the ordinarily recognised 

 acceptation of the word parasite, — quite recently, an Entozoon has 

 been discovered in the spinal chord of a sheep ! But to return to Mr. 

 Westwood's elaborate essay. 



" The insects composing the first of these two classes require for the 

 performance of their dread functions an organization of the parts of the 

 mouth, especially fitting them to pierce the skins and hides of the 

 quadruped upon the blood of which they subsist ; and we accordingly 

 find that it is precisely these insects which have the mouth-organs 

 most fully developed in the different families to which they respectively 

 belong. The Stomoxys calcitrans, and especially the different spe- 

 cies of Tabanus, are pre-eminent in this respect; and the formidable 

 array of lancets in the mouth of one of the latter insects is not to be 

 met with elsewhere among the whole of the flies composing the order 

 Diptera, to which they belong. The effects of the attacks of these 

 insects upon the horse are perceived by the drops of blood which flow 

 from the orifices caused by their bites, and sometimes these wounds 

 are so numerous that the beasts 'are all in a gore of blood.' A still 

 smaller species, named by Linneus the Culex equinus, also infests the 

 horse in infinite numbers, running under the mane and amongst the 

 hair, and piercing the skin to suck the blood. This insect, though 

 given by Linneus as a Culex, appears from his description to belong 



