ARIETES. 



ARMADILLO. 



... 



Although iiHMtly found upon finh it frequently leave* them, mul 

 mini* freely about in the wnt. r. Fish haw iu> instinctive knowledge 

 of them- creature* u their enemy, and it in amusing to watch ill n 

 basin of water the effort* which the stickleback will make to avoid 

 it minute persecutor ; but the efforts of the fish are in vain, for it in 

 opposed to a creature which baa the power of darting through water 

 with Mich rapidity that it is almost impossible to follow it with tlir 

 naked eye. The female* deposit their egg* from 400 to 1 S(>0 in number 

 on ttonea or other solid bodies. They are laid aide by side in row* and 

 glued together. They are hatched in about 35 days, and the young 

 resemble their parent* to a greater extent than is the case with many 

 of the forms of t'nlomoitrara. The bent account, with figures and 

 anatomy, of this pan*it<>, is givm in I>r. iioird'* ' History of the 

 British Entomostraca,' published by the Ray Society. Mr. Yarrell 

 ban given a figure of it in the second volume of his ' BritUh Fishes.' 



AKIKTKS. [AMMOSITE8.] 



AKII.I.rs, in Botany, i a fleshy expansion either of the umbilical 

 cord by which seeds are attached to the placenta, or of the placenta 

 itaelf. It is never formed till after the fertilisation of the seed, and 

 U only met with in a few plants ; its use is entirely unknown. The 

 most remarkable instance of the Arillus among species of common 

 occurrence is in the Spindle-Tree (Euonymtu Europina), in which it is 

 the fleshy red covering of the seed that renders that plant so 

 ornamental in the autumn and beginning of winter. Another 

 familiar case is the mace of the nutmeg ; this mil stance is, when 

 fresh, a crimson lacerated covering of the nut, which acquires its 

 pale-brown colour in consequence of the preparation it undergoes in 

 being dried ,and prepared for market Before the term was thus 

 accurately defined, it was applied to a variety of parts of exceedingly 

 different natures. 



ARISTOLOCHIA'CE^E, Sirtkwortt, consist of a small number of 

 genera which principally inhabit the hotter parts of the world. They 

 are in many cases used medicinally on account of their tonic and 

 stimulating properties ; and some of them ore reputed remedies for 

 the bite of venomous serpents. The distinguishing characters of the 

 order reside in the flowers, which have no corolla, and are constantly 

 divided into three segments ; the number of the cells of the fruit is 

 also three or six, and the stamens agree in the same ternary character ; 

 the fruit is always adherent to the calyx, or, as botanists say, inferior. 

 Notwithstanding the accordance which thus exists between Aritto- 

 lockiaeea and Monocotyledonous Plants in the ternary number of the 



AratotocJiur. 



1, A branch of Arittalarhla Siplui ; 2, one of It* flower* cut Icnitthwite, (bow- 

 Ing the Um<Ti lying in IU bottom ; S, a clunter of ntamrni ; 4, a wed-TrMcl j 

 S, the unc cut acroa* to abow It* aix cell* ; 6, a aced ; 7, a aeed cut through to 

 how the minute embryo lying In the albumen ; 8, an embryo much magnified. 



parts of their flowers, their structure is otherwise truly Dicotyledonous. 

 The arrangement of the woody matter of which their *tem is composed 

 is in longitudinal plate*, surrounding a central pith, and lurrounded 

 by bark ; but what is very curious, these plates are not placed in 

 concentric circles like most other exogenous plants, but continue to 

 i uniformly and uninterruptedly as long as the plant grows. 



[KxourNs.] The loaves aru veined like thoso of i x. . u'.i, and 



the vniliryu of the seed has two lobes. 



The most common plant* of this singular order are the dif 

 species of A tar inn, or, as the gardeners call them, Awirabaooa, little 

 Btemleas plants with dingy -brown flowers hidden among the leaves. 

 This colour, which in far from common in plant*, appear* charact . 

 of the wliol.j ..nl.T. f ur even in those species which have yellow 

 flowers, a brown stain seems to be mixed with the colour so as to 

 change it, or brown spots are scattered over the surface. The nfost 

 remarkable species of thegenu* AritiiJuchia are those which, in n. my 

 of the tropical parts of America, excite the wi.n.l.-r <( tr.n.-l! 

 the gigantic siise or grotesque appearance of the flowers, such as 

 A. cymhifera, the border of whose calyx resembles on.- of tin- lappeU 

 of a Norman woman'* cap, and measures 7 or 8 inches in 1< 

 A. cordijlora, and A. gignntta, the flowers of which are fn.u, 

 10 inches across, and are large enough to form bonnuts for tin- n;ith e 

 children. 



The properties of this order are generally tonic and stimulating. 

 Many of the species, as their common name implies, have had 

 pmjierties attributed to them which they are now known 

 .possess ; at the same time some of them are emetic and 

 purgative, and they contain undoubtedly plants which might be used 

 with advantage in medicine. Only one has been much used, the 

 Arittolochia Serpcntaria. [ARIBTOLOCHIA, in ARTS AND Sc. 1 >i v. | 



ARKTIZITE, one of the names for the group of minerals included 

 under Scapolite. [SCAPOLITK.] 



ARMADILLO (Datypiu, Linmeun), a genus of the class Mammalia 

 belonging to the order Edentata, and forming, with the allied genera 

 Chiamyphonu and Orycteroput, a small but very distinct family 

 intermediate between the Sloths and Ant-Eaters, and characterised by 

 the possession of molar teeth only. The Sloths [BRADYITS] have not 

 only the ordinary molar teeth of common quadrupeds, but are 

 likewise provided with large and powerful canines ; though, as for as 

 we know anything of their economy, they appear to be a purely 

 herbivorous family, and to be even incapacitated by other details of 

 their organisation for the capture or destruction of a living pri-y ; 

 whilst the Ant-Eaters [ACT-EATER] are not only deprived of canine 

 but likewise of molar teeth, consequently ore without teeth of any 

 description, and thus form the only family of the order Edentata that 

 literally answers to the name and definition. Nor are these the only 

 distinctions which subsist between the three families of edentulous 

 mammals which we have here indicated. Others are pointed out in 

 the articles just referred to, and it will be sufficient to mention, in 

 addition, that the Ant- Eaters differ from the other two families by the 

 wont of clavicles (a most important and influential element in the 

 anatomical structure of all vertebrated animals), and the Armadillo.", 

 the more immediate subject of our present consideration, by the 

 peculiar nature of their external covering. Instead of hair, the 

 armadillos are covered with a species of hard bony crust, forming 

 three bucklers on the head, shoulders, and rump, respectively, the two 

 latter being connected by a number of transverse moveable bonds, 

 very similar in form and appearance to the plate armour of the 

 middle ages, from which indeed these animals have acquired the 

 name of Armadillos a name of Spanish origin, which has been 

 adopted by English writers. These bucklers likewise hang down on 

 each side, so as to form an effectual protection to the belh 

 partially to cover the legs and feet ; whilst the pliancy produced by 

 the moveable bands interposed between the bucklers of the rump :m.l 

 shoulders, and which are themselves connected by the soft pliant skin 

 of the animal, permits the most varied and rapid motions. The 

 bucklui & themselves, as well as these connecting moveable bands, are 

 composed of numerous small polygonal plates, placed contiguous to 

 one another like the stones of a mosaic pavement, but without any 

 actual articulation, and they ore incapable of separate motion. The 

 whole thus forms a kind of shelly buckler not unlike that of a lobster ; 

 and though incapable of actual motion, yet the thinness of the shell, 

 and, during life, the pliancy occasioned by the animal oil which 

 penetrates it, allow it to yield to a certain degree, and thus to 

 accommodate itself in some measure to the motions of the body. But 

 the great and principal motions, as already observed, are entirely due 

 to the moveable transverse bonds, interposed between the two 

 principal bucklers of the body, and which vary in number according 

 to the species, and even within certain limits according to the age, 

 sex, or individual. These are situated immediately above the loins, 

 or in the region to which all the principal motions of the animal 

 economy have been assigned ; the bucklers of the head and shoulders 

 are entirely disunited, and have none of these moveable Immls 

 interposed between ; but that of the head projects considerably 

 backwards, and affords complete protection to the neck, which i 

 indeed no short as to be barely distinguishable. 



The throat, breast, belly, and thighs of the armadillo are naked, or 

 covered with a thick granulated skin, thinly furnished with warts or 

 tubercles, which give origin to a few coarse bristly hairs. The com- 

 mimures of the moveable bands on the loins are likewise provided with 

 number of long hair* ; but with this exception the body is covered 

 only by its peculiar shell. The tail is straight, round, thick, and 

 pointed ; it is adapted at the root to a notch or cavity in the posterior 

 edge of the buckler of the croup, and, with the exception of one 



