Page:The American Cyclopædia (1879) Volume VI.djvu/675

 ENTOMOLOGY lerally the smallest ; a sting at the end of the abdomen ; transformation complete ; larvae like maggots, or slugs, or caterpillars; pupae with the legs and wings unconfined. VII. Diptera (flies, mosquitoes, &c.), with a horny or fleshy proboscis, two wings and two balancers or poisers behind them ; transformation complete ; larvae footless maggots, with the breathing holes generally in the hinder part of the body ; pupse usually incased in the dried skin of the larvae, but sometimes naked, in which case the wings and legs are visible, and more or less free. Among the smaller groups, the order strepsiptera (Kirby), or rhipiptera (Latr.), con- tains minute insects which undergo their trans- formations within the bodies of bees and wasps ; the maggot-like larvae live between the rings ; the females are wingless, and never leave the body of their host ; the adult males have two very short members instead of fore wings, and two very large hind wings ; the sharp-pointed jaws are adapted for piercing rather than bi- ting. Their systematic position is not precisely determined; Latreille places them between lepidoptera &nd diptera, though he thinks them most nearly allied to some of the hymenoptera. The order aptera (Leach), suctoria (De Geer), siphonaptera (Latr.), or aphaniptera (Kirby), is constituted by the flea tribe, which seem to be intermediate between hemiptera and diptera. The earwigs, included by most entomologists among orthoptera, form the order dermaptera (Leach), or euplexoptera (.Westwood). The spider-flies, ticks, &c., alluded to at the close of the article DIPTERA, form the order homa- loptera (Leach). The May flies were separated from the neuroptera and elevated to an order trichoptera by Kirby. The thysanoptera of Haliday consist of the minute insects of the thrips tribe, generally classed with the hemip- tera; other hemiptera, as the harvest flies, plant lice, &c., have been separated by the English writers under the name of homoptera. Burmeister has separated from neuroptera those specie* which undergo only a partial metamorphosis into the order dictyotoptera. Naturalists generally have been disposed to rank insects in the animal scale below mollusca, though many of their vital functions, as of locomotion and perception, indicate a supe- riority in the former. Mr. Kirby and other English entomologists have accorded the pre- cedence to insects, in opposition to Cuvier and Lamarck, who placed the mollusca first on account of their system of circulation. In the branch of articulata, the position of insects is well given by Oken, when he says that "lepi- doptera are born as worms, then pass into the condition of Crustacea, and are finally developed into true insects, exemplifying the natural order of gradation of the three classes of ar- ticulata." For interesting and conclusive ob- servations on the position that worms are the lowest, Crustacea the intermediate, and insecta the highest among articulata, see the paper by Agassiz, above alluded to, in vol. ii. of the ENTOZOA 663 "Smithsonian Contributions." In vol. i. of " Contributions to the Natural History of the United States," in the highest class (insecta) of articulata he establishes the three orders of my- riapods, arachnids, and insects proper, the last therefore being the highest order of the high- est class, and the lepidoptera (butterflies and moths) the highest division in this order. MTOMOSTRACA, the lowest order of crusta- ceans, deficient in the segments, feet, and ab- dominal appendages of the higher forms. They have normally five or six cephalic rings, and eight or nine posterior ones belonging to the foot series. They include the carcinoids, like caligus and argulus, minute forms, parasitic or marine and fresh- water fishes ; the ostra- coids, minute forms like the daphnia of fresh waters, with the larger marine cirripeds or barnacles; the limuloids, or horseshoe crabs; and the microscopic rotifers, radiate in appear- ance but crustacean in structure, whose organs, of locomotion are cilia around the head. They appeared in the early Silurian age. ENTOPHTTES. See EPIPHYTES. EVTOZOA (Gr. ivr6^ within, and Cwov, animal), a group of invertebrate animals, which during some period of their existence live within and derive nourishment from the bodies of other animals, and with few exceptions belong en- tirely to the class of helminths or worms. Animal parasites form in fact a sort of sub- fauna, and their number is only to be estimated by the extent of the animal kingdom. The classification of entozoa has been attempted by many eminent zoologists since the days of Rudolphi, who may be considered the father of helminthology ; but only recently, and chiefly through the labors of a few observers in Ger- many, has it attained the position of a true science. Cuvier refers the entozoa to the class radiata, and subdivides them, following the plan of Rudolphi, into tcenioidea or tapeworms, trematoda or flat worms, nematoidea or round worms, and acanthocephala or hooked worms. More correctly, however, they belong to the articulata, though their type is a degraded one, and some of them even approach in structure the mollusca. Adopting this arrangement, we can best explain the progress and present state of heminthology by considering these subdi- visions separately. Tcenioidea, cestoidea, ste- relmintha, tapeworms. These parasites in their mature state inhabit the intestines of all classes of vertebrate animals. In their tran- sitional state or immature stage they occur as cysts in the tissues and organs of such crea- tures as form the food of their true bearers or hosts. These cysts, of which the measles in swine are an example, in the early days of science were not looked upon as of an animal nature, and were called hydatids and acephalo- cysts ; and not until the latter part of the 17th century was their true character recognized. In the 18th, many observers, and especially Gotze, noticed that their heads closely resembled those of the tapeworms. His observations were