Page:The New International Encyclopædia 1st ed. v. 01.djvu/678

ANNUITY. specific personal or real estate. In cither case. if given with words of inheritance, it will de- scend as real property, but for all other purposes it will be treated as personal property. In this respect it differs from a rent charge ( q.v. ), with which it is often confused, but which is always charged on specific real estate and, whether in- heritable or not, is always treated as real prop- erty. Annuities are classed by Blackstone {Commenlaries, Book ii., p. 40) with rents, fran- chises, etc., as incorporeal hereditaments (q.v.). Like other species of property, they are generally alienable, except in jurisdictions -where by statute beneficiaries of trusts for the payment of annuities are not allowed to alienate their inter- ests under the trust.

Consult: Blackstone, Comm.eniaries on the Laws of England; Kent, Commentaries on American haw, and the authorities referred to under the title.

AN'NULAR ECLIPSE. See. AN'NULA'RIA (Lat. annulns, a small ring). Agenus of fossil plantsfound in rocks of Devonian, Carboniferous, and Permian ages, allied to the modern Equisetacea», or Seouring-rushes, and consisting of fluted annulated stems bearing numerous narrow leaves arranged in whorls at the ring-like joints. Annularije, for so long a time considered to be plants of a distinct genus, are now known to be, together with the genera Asterophyllites and Sphenophyllum, merely heteromorplious leaves of the Calamites (q.v.).

AN'NULA'TA, or ANNELI'DA (Lat. annu-lns. a little ring), A ])hylum of animals, the annelids, comprising a large group of segmented, worm-like forms, mostly included by Linn;exis in his class Vermes. They have a more or less elongated body, which is always composed of niunerous segments. The first of these as- sumes, in many, the character of a head, but in some the head is not clearly set off from the trunk. They have no jointed appendages, but most of them are provided with bristles and hairs, called setcc, often in numerous bun- dles, which are of use to them in locomotion; some, which want these, are furnished with suckers at the extremities, and employ them for this purpose; some remain fixed in one place. Their "bodies are always soft, and without external or internal skeleton; but some of them form for themselves a calcareous covering by exudation; others form coverings partly by exudation anil partly by agglutination. Their blood is generally red, but not from red corpiiseles, as in vertebrates; sometimes it is gi-eenish or yellowish. The circulatory system is well-developel in most annelids, though a few alierrant forms have it gicatly reduced or even entirely wanting. It is generally what is called a closed system; that is, the vessels of which it is composed are entirely slmt off from communication with the body cavity. But in the leeches there is no sharp distinction between blood-vessels and body cavity. Tlicre are always longitudinal vessels, usually two. sometimes four, the dorsal or lat- eral (if which pulsate more or less. These longi- tudinal vessels are connected by a large number of transver.se vessels. Some of these near the anterior end of the body are occasionally larger than the rest, and are called ''hearts," but there is no true heart. See ;.

The nervous system consists of a pair of ganglia lying above the oesophagus, known as the brain, from which the nerve trunlcs arise. Usually there aie two such trunks, which pass downward and back^•ard around the ajsophagus, meeting in the mid-ventral line and running backward to the rear of the body as a double cord. On this there are ganglia in each segment. The sense of touch is usually acute in annelids, and is often localized in tentacles and papillte. Many species have eyes more o^ less highly organized; some have sensory pits, supposed to be smelling organs; some have sensory papilhc, which from their occurrence around the mouth are supposed to be organs of taste; and a very few have oto- eysts, or positional organs. In all annelids, ex- cept a few aberrant forms, excretion takes place- by means of ncphridia, and these are usually ar- ranged a pair in each segment. These ncphridia are coiled tubes, one end widened to form a fun- nel and opening in the bod.v cavity, and the other ojiening to the exterior. See Nervou.s S^'STEM. Respiration is either by gills, which are of very 'arious structure and appearance, or through the surface of the body or some part of the alimentary canal. The latter varies greatly ith the habits of the worms, but the anal open- ing is always at the posterior end of the body. The muscular system is usually well develo])ed, for many of these worms are very active ani- mals. The sexes are generally sejiarate, but many annelids are hermaphrodites. Nearly all lay eggs, and these are sometimes provided with a shell. See ; ;.

Annelids are widely distributed over the world; while the majority are marine, a large nimiljcr are found in fresh water or in the earth. 51any are carnivorous, liut scinie are almost whol- ly vegetable feeders. Some are sluggish, but the majority are active, and some move with remarkable rapidity. They vary gi-eatly in size, some being almost microscopic, while others are several feet long. They are usually dull- colored, but some, especially tropical species, are gorgeously airayed. Aside from the part they play in the economy of nature as soil producers and scavengers, they are of little use to man. Leeches were formerly (and are still sometimes) used in medicine for blood-letting, and a few species are used as food by savages, notably the palolo-worm (q.v.).

The classification of the annelids has always been a mnttev of great difticulty, as there are several other groups to which they seem to be related or which they superficially resemble. The matter is not definitely settled, but it seems best now to regard them as a jihylum, or type, coordinate with Mollusca, Arthropoda, etc., and containing two well-marked clas.ses, and two others whose relationships are very obscure. The largest and most important of these classes is that of the Chwtopoda. in which the blood system is closed and the external rings of the body correspond to the internal segments. They have locomotive organs in the form of sci(r. or appendages provided with them. The class includes a very great number of species of widely different structure and appearance, and the most convenient, though possibly not the most natural way to divide it is into three groups, Polychaita, Oligochoe- la. and Myzostomida. The last named are a very small gronji of curious, degenerate annelids which live parasitically on crinoids. The body