"The larva of this species may be obtained from almost any horse that has been much the preceding year at grass, and exposed to these flies, and will be found during the summer months sticking more or less within the verge or opening of the anus, adhering to its soft lining, and producing considerable irritation and uneasiness. Indeed, I once well remember being on a tour of pleasure in the Isle of Wight, and experiencing much annoyance from these larvæ. The little horse I had hired for the journey became so lazy and unwilling to go on, and moved so awkwardly, that I could not keep pace with my company, and I was at a loss how to proceed; but on casually taking up the tail, I discovered three or four of these insects hanging to the rectum, and their removal instantly proved a cure." For more ample particulars, the reader is referred to the book itself, which is entitled "AN ESSAY ON BOTS IN THE HORSE AND OTHER ANIMALS." It will, in the pages of the original work, be seen that Mr. Clark more than suspected the existence of other species of the same family; but, as no positive knowledge has yet been gained, we must await patiently the inquiries of those to whom this branch of science belongs. However, the writer must dissent to Mr. Clark's conclusion, that "bots are harmless, if not beneficial." How far does such a supposition agree with the perforated stomach, preserved at the Royal Veterinary College? How far does it accord with the ragged coat and unthrifty aspect by which the presence of the parasites is ascertained? How, when crediting such a conjecture, are we to account for the horror exhibited by the horse at the approach of the fly; and how can we interpret Mr. Clark's experience in the Isle of Wight?