Page:Encyclopædia Britannica, Ninth Edition, v. 12.djvu/647

Chinese population is estimated at 33,560 (Deutsches Handels Archiv, 1880); and in 1878 there were fifteen foreign residents.

See Journ. of R. Geogr. Soc., 1862; and Blakiston, Five Months on the Yang-tze-Keang, 1862.

ICHNEUMON (Herpestes), a genus of small carnivor ous mammals belonging to the family Viverridte, and resembling the true civets in the elongated weasel-like form of the body and in the shortness of the limbs. There are, according to Gray (British Museum Catalogue, 1809), 22 species of ichneumons, the great majority of which are confine,! to the African continent, the remainder occurring in Persia, India, and the Malay archipelago, and one, the Andalu-sian ichneumon (H. Widdringtunii, Gray), in the Sierra Morena of Spain, the last probably an African straggler. The Egyptian and Indian ichneumons are the forms best known. The former (Herpestes ichneumon, L.) is an inhabitant of Egypt and the north of Africa, where it is known to foreign resi dents as " Pha- Egyptian Ichneumon, raoh s rat. When fall grown it is about the size of the domestic cat. It is covered with a fur of long harsh hairs of a tawny grey colour, darker on the head and along the middle of the back, its legs reddish and its feet and tail black. It feeds on rats and mice, birds and reptiles, and for this reason is occasionally domesticated. Its fondness for eggs leads it to search for those of the crocodile, buried as these usually are beneath a thin covering of sand on the river banks; and its services in thus checking the multiplication of those reptileswere so appreciated bythe ancient Egyptians that they regarded the ichneumon as a sacred animal, and when it died buried it, says Herodotus, "in holy reposi tories." It is, however, equally fond of poultry and their eggs, and its depredations among fowls considerably detract from its undoubted merits as a vermin-killer. During the inundations of the Nile it is said to approach the habitations of man, but at other seasons it keeps to the fields and to the banks of the crocodile-frequented river. The Indian ichneumon or mungoos (Herpestes griseus, Desm.) is con siderably smaller than the Egyptian form ; its fur is of a pale grey colour, the hairs being largely white-ringed, while the cheeks and throat are more or less reddish. Like the preceding species, it is frequently domesticated, and is then put to a similar use. It is especially serviceable in India as a serpent killer, destroying not only the eggs and young of these creatures, but attacking without hesitation and killing the most venomous adult snakes. The fact that it invariably survives those encounters has led to the belief that it either enjoys immunity from the effects of snake poison, or that after being bitten it has recourse, as the Hindoos have always maintained, to the root of a plant as an antidote. Neither of these suppositions has stood the test of scientific examination, for it has been found that when actually bitten it falls a victim to the poison as rapidly as other mammals, while there is no trustworthy evidence of its seeking a vegetable antidote. The truth seems to be that the mungoos by its exceeding agility and quickness of eye avoids the fangs of the snake while fixing its own teeth in the back of the reptile s neck. The whole Thanatophidia of India stand in awe of this tiny but tenacious mammal, and seek to escape from its presence. The mungoos, on the other hand, never hesitates to attack; the moment he sees his enemy, " his whole nature," says a recent spectator of one of those fights, " appears to be changed. His fur stands on end, and he presents the incarnation of intense rage. The snake invariably attempts to escape, but, finding it impossible to evade the rapid onslaught of the mungoos, he raises his crest and lashes out fiercely at his little persecutor, who seems to delight in dodging out of the way just in time. This goes on until the mungoos sees his opportunity, when like lightning he rushes in and seizes the snake with his teeth by the back of the neck close to the head, shaking him as a terrier does a rat. These tactics are repeated until the snake is killed." The mungoos is equally dexterous in killing rats and other four-footed vermin.

ICHNEUMON-FLY is a general name applied to parasitic insects of the section Pupivora (or Entomophaga), order Hymenoptera, from the typical genus Ichneumon, belonging to the chief family of that section, itself fanci fully so called after the Egyptian mammal (Jlerpestes), notorious for its habit of destroying the eggs of reptiles. The species of the families Ichueumonida?, Braconidce, Evaniidce, Proctotrypidce, and Chalcididce are often indis criminately called " Ichneumons," but the term is perhaps properly applicable only to the first and second of these, which are respectively equivalent to the Ichneumones genuini and /. adsciti of older naturalists, chiefly differing in the former having two recurrent nerves to the anterior wing, whilst the latter has only one such nerve. The Ichneumo- nidce proper are one of the most extensive groups of insects, and have been much studied by entomologists since the time of Linnaeus and Gravenhorst. Their sexual differences of colour, &c., are, however, often so great that fresh discoveries are constantly being made with regard to their true specific relations, as well as new species detected by biological observers. Gravenhorst described some 1650 European species, to which considerable subsequent addi tions have been made ; and at the latest computation of the English Ichneumonidoe (in 1872, by the Rev. T. A. Marshall), 1186 species, contained in 136 genera, were recognized, 439 Braconidce being also enumerated. There are 6 subfamilies of the Jchneumonida , viz., the Ichneu- monides, Cryptides, Agrioty/tides, Opkionides, Tryphonides, and Pimplides, differing considerably in size and facies, but united in the common attribute of being in their earlier stage parasitic upon other insects. They have all long narrow bodies ; a small free head with long filiform or setaceous antennae, which are never elbowed, and have always more than sixteen joints ; the abdomen attached to the thorax at its hinder extremity between the base of the posterior coxae, and provided in the female with a straight ovipositor often exserted and very long; and the wings veined, with perfect cells on the disk of the front pair.

The parasitic habits above alluded to render these flies

of very great importance in the economy of nature, as they effectually serve to check any inordinate increase in tho numbers of injurious insects. Without their aid, indeed, it would in many cases be impossible for the agriculturist to hold his own against the ravages of his minute hexapod foes, whose habits are not sufficiently known to render artificial checks or destroying agents available. The females of all the species are constantly on the alert to discover the proper living food for their own larvae, which are hatched from the eggs they deposit in or on the eggs, larvae, or pupa3 of other insects of all orders, chiefly Lepidoptera, the caterpillars of butterflies and moths being specially attacked (as also are spiders). Any one who has watched insect life, even in a suburban garden, during summer, can hardly have failed to notice the busy way in which the parent ichneumon, a small four-winged fly, with constantly vibrating antennae, searches for her prey ; and the clusters of minute cocoons round the remains of some unfortunate cabbage-butterfly caterpillar, which has had just

enough vitality left in it to crawl instinctively to a proper