INVERTEBRATA INVESTITURE 325 tiost peak in Britain, rises to a height of 4,406 ft. ; Cairngorm is 4,090 ft. high ; and Tomnahurich, an isolated hill near Inverness, 1,984ft. Veins of lead and silver and small quantities of iron ore have been discovered, but no coal. The chief rivers are the Spey, Ness, Beatily, and Garry, all of which have valuable salmon fisheries. Lakes occupy 132 sq. m. of the area. The largest is Loch Ness, so deep that it never freezes ; with its continu- ations and connections, it bisects the county from N. E. to S. W. Many of these lakes are surrounded by picturesque scenery. The Gaelic language, excepting in the town of Inverness, is more prevalent than English. Agriculture is prosperous; oats are the main crop. But tillage is secondary to the raising of cattle and sheep, the former generally of the Skye or Kyloe breed, and the latter Cheviot or Linton. IJVVERTEBRATA, a negative term in zoology, employed by Lamarck to designate animals des- titute of a vertebral column or backbone. Ex- clusive of the protozoa, these constitute three out of the four great divisions of the animal kingdom, viz., articulates, mollusks, and radi- ates ; the remaining division consists of the ver- tebrates, or those having an internal skeleton with a backbone for its central support, inclu- ding man and other mammals, birds, reptiles, amphibians, and fishes. The articulates, char- acterized by a jointed body, include insects, arachnids, centipedes, crustaceans (as crabs and lobsters), and worms; the mollusks are those generally denominated shell-bearing animals; the radiates include the echinoderms (or sea urchins, star fishes, and holothnrians), the aca- lephs or jelly fishes, and the polyps (like hydra, actinia, and the coral animals). There is no homology or affinity between the structural type of the vertebrates and invertebrates, though there may be analogy; for instance, the head of an insect is not homologous with the head of a man, a bird, a reptile, or a fish, as it has no distinct brain cavity nor cranial vertebra?, yet its sense organs and other parts perform the same functions. Aristotle distinguished in- vertebrates from vertebrates, calling the former avalfia (bloodless) and the latter kvaijia (having blood); Oken made the same distinction in his gut animals and flesh animals, and Ehren- berg in his ganglioneura and myeloneura ; even Lamarck was aware that in his inverte- Itrata all the organs are contained in a single cavity, while in the vertebrate there are dis- tinct cavities for the nervous system and the organs of vegetative life. Lamarck divided the invertebrates into two orders and twelve classes, viz. : apathetic animals, with the five classes of infusoria, polypi, radiaria, tunieata, and uermes; and sensitive animals, with the seven classes of insects, arachnids, Crustacea, annelids, cirripeds, concJiifera, and mollusks; all distinguished from vertebrata, or intelligent animals. The development of the embryo and the methods of reproduction in the inverte- brates are different from those of the verte- brates. In the radiates the germ surrounds the yolk like a crust, from which the more animated parts are derived, the alimentary canal being formed from the central mass ; reproduction may also take place by buds or by transverse division in the polyps and jelly fishes, the latter also presenting the curious phenomena of alternate generation. In .artic- ulates the embryo is formed at the lower part of the yolk, with its dorsal surface toward the latter, so that the yolk is enveloped from be- low upward, the uniting suture being upon the back. In mollusks the yolk is introduced from the lower side of the animal, asin vertebrates, but there is no upper cavity for the nervous sys- tem, as in the latter. It is thus evident that the term invertebrata is not equivalent in zoolo- gical precision to, and is far more comprehen- sive than, the vertebrate division ; the oyster, the butterfly, the star fish, all invertebrates, have nothing in common but the absence of a vertebral column. Invertebrates include by far the most numerous and diversified forms in the animal kingdom ; in them we find many important physiological questions answered, and by them we understand otherwise inex- plicable problems of animal life and of its re- lations to changes in the earth's surface; in them we see a circulation of blood without a heart or without distinct vessels, respiration effected by a vascular integument, the nervous system reduced to its essential elements of ganglia with connecting cords, the external skeleton enclosing the muscles and organs, the plant-like mode of reproduction and of true hermaphroditism, and the multiplication of or- gans independently performing the same func- tions (as digestive sacs, gills, locomotive ap- pendages, &c.). The different classes will be described more fully in their respective order. The whole subject is most learnedly treated by Prof. Owen in his "Lectures on the Inverte- brate Animals" (1843). INVESTITURE, the public delivery of a feud or fief by a loM to his vassal. Blackstone says : " Investitures, in their original rise, were probably intended to demonstrate, in conquered countries, the actual possession of the lord, and that he did not grant a bare litigious right, but a peaceable and firm possession. At a time when writing was seldom practised, a mere oral gift, at a distance from the spot that was given, was not likely to be long or accurately retained in the memory of bystanders who were very little interested in the grant." In- vestiture was performed by the presentation to the person invested of some symbol of au- thority and possession. Thus, when lands were transferred, it was customary for the grantor to give the grantee a turf as bearing resemblance to the property transferred. In ecclesiastical history, by the right of investi- ture was meant that claimed by the temporal lord of presenting a prelate with the ring and crosier, the acknowledged emblems of episco- pal and abbatial jurisdiction. Before the in-
