in the stomach are very various, "often not more than half a dozen, "at other times more than a hun"dred, and if some accounts might "be relied on, even a much greater number than this. They hang "most commonly in clusters, being "fixed by the small end to the inner "membrane of the stomach, which "they adhere to by means of two "small hooks or tentacula. When "they are removed from the stomach "they will attach themselves to any "loose membrane, and even to the "skin of the hand." "The body of the larva is com"posed of eleven segments, all of "which, except the two last, are "surrounded with a double row of horny bristles, directed towards "the truncated end, and are of a "reddish colour, except the points, "which are black. These larvæ " evidently receive their food at the "small end, by a longitudinal ap 66 perture, which is situated between "two hooks or tentacula. Their "food is probably the chyle, which, "being nearly pure aliment, may 66 go wholly to the composition of "their bodies without any excre ❝mentitious residue, though on dis"section the intestine is found to contain a yellow or greenish mat "ter, which is derived from the co"lour of the food, and shews that "the chyle, as they receive it, is not "perfectly pure,” 66 They attain their full growth "about the latter end of May, and ❝are coming from the horse from "this time to the latter end of June, ❝or sometimes later. On dropping to the ground, they find out some ❝ convenient retreat, and change to "the chrysalis; and in about six or seven weeks the fly appears." Clark I have only to add, that the most successful method of obtaining the flies from the chrysalis is by taking the larvæ, when fresh dropped from the horse, and immediately enclosing them separately in balls of fresh horse-dung, which must be kept in a warm situation, and sprinkled every second or third day with water: the animals will thus be preserved in a proper degree of warmth and moisture, and the flies will make their appearance in the usual time. Oestrus ovis, or the sheep gad fly, is so named from its larva inhabiting the nostrils and frontal sinuses of sheep in particular, though it is also found in similar situations in deer and some other quadrupeds. It is a smaller species than either of the two preceding, and is of a whitish grey colour, with the thorax marked by four lon gitudinal black streaks, and the ab domen speckled with black. 1e larvæ are nearly as large as those of the oestrus equi, and, according to the observations of Mr. Clark, are of a delicate white colour, flat on the under-side, and convex on the upper; having no spines at the di visions of the segments, though they are provided with tentacula at the small end. The other is truncated, with a prominent ring or margin. When young, these larvæ are per fectly white and transparent, but as they increase in size, the upper side becomes marked with two transverse brown lines on each segment, and some spots are seen on the sides. They move with considerable quickness; holding with their tentacula as a fixed point, and drawing up the body towards them. Mr. Clark, in his description of this specics, observes that he has mostly found the larvæ in horns and frontal sinuses of "The manner," says Mr. Clark, "in which this species deposits its ova, has, I believe, not been de"scribed; nor is it easy to see, "though close to the animal at the "time, exactly in what way this is "accomplished, owing to the ex"treme agitation of the sheep; but "the motions of the sheep after"wards, and the mode of de"fence it takes to avoid it, can "leave but little doubt that the 66 egg is deposited on the inner mar 66 66 The other British oestri, are the 0. hæmorrhoidalis of Linnæus, whose larva, like that of the O. equi resides in the stomachs of horses, and the O. veterinus of Mr. Clark, the larva of which is also found in similar situations. The O. hæmorrhoidalis is about the size of a common window fly, with pale dusky wings, brown thorax, abdomen white at the base, black in the middle, and red at the tip. The O. veterinus is nearly of similar size with the O. equi, and is entirely of a ferruginous colour, with the abdomen more duský towards the tip. The exotic oestri are probably numerous, but are at present very little known. Whether the formidable African fly, described by Mr. Bruce, under the name of zimb*, or tsaltsalya may be referred to this genus or not, I shall not pretend to deter mine; there are, however, some particulars in its history, which would lead one to suppose it an oestrus. gin of the nostril. The moment "the fly touches this part of the sheep, they shake their heads, "and strike the ground violently "with their fore-feet; at the same "time holding their noses close to "the earth, they run away, looking 66 about them on every side, to see "if the fly pursues: they also "smell to the grass as they go, lest "one should be lying in wait for "This insect," says Mr. Bruce, If they observe one, they "is a proof how fallacious it is to 66 gallop back, or take some other "judge by appearances. If we "direction. As they cannot, like "consider its small size, its weak"the horses, take refuge in the ness, want of variety or beauty, 66 water, they have recourse to a "nothing in the creation is more "rut, or dry dusty road, or gravel-contemptible and insignificant. pits, where they crowd together Yet, passing from these to his his* Bruce's Travels, vol. I. p. 388, and vol. V. p. 188. ❝ them. VOL. XLVII. 66 3 G tors 66 tory, and to the account of his 66 powers, we must confess the very 66 great injustice we do him from "want of consideration. We are "obliged, with the greatest sur"prise, to acknowledge that those "huge animals the elephant, the rhinoceros, the lion, and the ti66 ger, inhabiting the same woods, are still vastly his inferiors, and "that the appearance of this small << insect, nay, his very sound, "though he is not seen, occasions 66 66 more trepidation, movement and "disorder, both in the human and "brute creation, than would whole ❝ herds of these monstrous animals "collected together, though their number was in a ten-fold propor❝tion greater than it really is. "This insect is called zimb; it "has not been described by any naturalist. It is in size very little larger than a bee, and his wings, which are broader than those of a "bee, placed separate like those of 66 a fly they are of pure gauze, "without colour or spot upon "them; the head is large, the up66 per jaw, or lip, is sharp, and has "at the end of it a strong pointed hair, of about a quarter of an " inch long; the lower jaw has two of these pointed hairs, and this pencil of hairs, when joined "together, makes a resistance to the finger nearly equal to that of a strong hog's bristle. Its legs 46 are serrated in the inside, and the whole covered with brown hair or down. As soon as this "plague appears, and their buzzing is heard, all the cattle forsake "their food, and run wildly about "the plain, till they die, worn out with fatigue, fright, and hunger. "No remedy remains for the residents on such spots, but to leave What enables the shepherd to "perform the long and toilsome journies across Africa is the ca"mel emphatically called the ship of the desert. Though his size is “immense, as is his strength, and his body covered with a thick skin, "defended with strong hair, yet "still he is not capable to sustain "the violent punctures the fly "makes with his proboscis. He "must lose no time in removing to "the sands of Atbara; for when (" once attacked by this fly, his "body, head, and legs, break out "into large bosses, which swell, "break, and putrify, to the certain "destruction of the creature. Even "the elephant and rhinoceros, who, "by reason of their enormous "bulk, and the vast quantity of "food and water they daily need, "cannot shift to desert and dry move to the next sand in the be"ginning of the rainy season, to "prevent all their stock of cattle from being destroyed. This is hot a partial emigration; the in- "from enjoying the help or labour "habitants of all the countries, of any beasts of carriage. It de"prived them of their flesh and milk "for food, and gave rise to another "nation, whose manners were just the reverse of the first. These were the shepherds, leading a "wandering life, and preserving these immense herds of cattle, by "conducting them into the sands beyond the limits of the black earth, "and bringing them back again when the danger from the insect "from the mountains of Abyssinia, "northward, to the confluence of "the Nile and Astaboras, are "once a-year obliged to change "their abode, and seek protection "in the sands of Beja; nor is there any alternative, ог means of "avoiding this, though a hostile "band was in their way, capable of spoiling them of half their sub แ stance. "Of all that have written upon "these countries, the prophet "Isaiah alone has given an account "of this animal, and the manner of "its operation. And it shall come to pass. in that day, that "the Lord shall hiss for the fly "that is in the uttermost part of the "rivers of Egypt.-And they shall come, and shall rest all of them "in the desolate vallies, and in the "holes of the rocks, and upon all "thorns, and upon all bushes.'"Isaiah, ch. 17, v. 18, 19." By the expression of resting in the desolate vallies, &c. Mr. Bruce understands the prophet to mean, "that they shall cut off from the "cattle their usual retreat to the "desert, by taking possession of "those places, and meeting them "where ordinarily they never .. come, and which, therefore, are " the refuge of the cattle. 66 not till this time, and by means of "this insect, that God said he would separate his people from the "Egyptians. And it would seem "that then a law was given to "them that fixed the limits of their "habitation. It is well known, as "I have repeatedly said, that the "land of Goshen, or Geshen, the "possession of the Israelites, was a land of pasture, which was not "tilled or sown, because it was not "overflowed by the Nile. But the "land overflowed by the Nile was "the black earth of the valley of "Egypt, and it was here that God confined the flies; for, he says, it shall be a sign of this separa"tion of the people, which he had "then made, that not one fly "should be seen in the sand, or "pasture ground, the land of Go"shen, and this kind of soil has 66 ever since been the refuge of all "cattle emigrating from the black "earth, to the lower part of Atbara. Isaiah, indeed, says, that 3 G 2 the the fly shall be in all the de"sert places, and consequently the "sands; yet this was a particular "dispensation of providence, to "answer a special end, the desola"tion of Egypt, and was not a "repeal of the general law, but a "confirmation of it; it was an ex"ception, for a particular purpose, "and a limited time." Mr. Bruce adds that this insect has no sting, but that its motion is more rapid than that of the bee, and resembles that of the gad-fly in England; and that there is something particular in its sound or buzzing. It is a jarring noise, together with a humming, which induces Mr. Bruce to suppose that it proceeds, at least in part, from a vibration made with the three hairs at the snout. He observes farther, that the Chaldee version is content with calling this animal simply zebub, which signifies the fly in general, as we express it in English. The Arabs call it simb in their translation. The Ethiopic translation calls it tsaltsalya, which is the true name of this particular fly in Geez, and was the same in Hebrew. markable species, without any particular division of the genus. One of the largest of the European spiders is the aranca diadema of Linnæus, which is extremely common in our own country, and is chiefly seen during the autumnal season in gardens, &c. The body of this species, when full grown, is not much inferior in size to a small hazel nut: the general colour of the animal is deep chesnut-brown, approaching to reddish in some specimens, and the abdomen is beautifully marked by a longitudi nal series of round or drop-shaped milk-white spots, crossed by others of similar appearance, so as to represent in some degree the pattern of a small diadem. This spider, in the months of September and October, forms, in some convenient spot or shelter, a large round, close, or thick web of yellow silk, in which it deposits its eggs, guarding the round web with a secondary one of a looser texture. The young are hatched in the ensuing May, the parent insects dying towards the close of autumn. The male of this species is distinguished by hav ing the back crossed by four or five black-brown bars. The aranea the common spiders, serves to diadema, being one of the largest of exemplify some of the principal characters of the genus in a clearer manner than most others. At the tip of the abdomen are placed five* papillæ or teats, through which the insect draws its thread; and as each of these papilla is furnished with a vast number of foramina or outlets, disposed over its whole surface, it follows that what we commonly term In some species four; and in some are two smaller papillæ, the nature of which is doubtful. |