337 



ATHAXAS. 



ATROPA. 



333 



are naked and of a brown colour, with a few long black hairs thinly 

 scattered over them ; the hair of the head is long, matted, and 

 directed forwards over the forehead, that of the body and members 

 very long and thick ; the fingers, both upon the anterior and posterior 

 extremities, are long, slender, and nearly naked ; the tail is considerably 

 longer than the body, very thick and covered at the base with close 

 shaggy hair, but attenuated towards the point, where it is more 

 sparingly furnished with shorter hair, and entirely naked underneath. 

 This species inhabits Guyana and some of the neighbouring provinces 

 of Brazil. Von Sack, in his ' Voyage to Surinam,' gives the following 

 account of its manners under the name of Quata, with which species 

 its general appearance probably causes it to be frequently confounded. 

 " The Quata," says this author, " is of a very docile disposition, and 

 capable of being quite domesticated. I have seen a pair of them at a 

 gentleman's house at Paramaribo which were left quite at liberty. 

 When the female negroes were employed at their needlework, they 

 used to come and sit amongst them, and play with a piece of paper, 

 and afterwards go out to gambol upon the trees, but never went over 

 to the neighbouring gardens ; and they knew well the usual hour of 

 dinner at their master's, when they would come to the gallery, look 

 in at the windows, though without attempting to enter into the room, 

 being aware that this was a liberty not allowed them ; they therefore 

 patiently waited for their dinner on the outside." 



ATHANAS (Leach), a genus of the Long-Tailed Crustacea, bearing 

 much resemblance to Lyxmata (Risso), from which it differs in having 

 the first pair of feet of larger size than the rest, while the second pair 

 of Lytmata are the largest. It is small in size, and has been taken on 

 the south coast of England and on the shores of France. 



ATLANTA, a genus of the Heteropodous Mollmra, of Lamarck, 

 which Cuvier places next to Carinaria. The animal is very small, 

 and the shell very delicate. 

 Lamanon thought that he 

 had discovered in one of 

 these shells the original of 

 the fossil Ammonites, or 

 Cormut Ammoni, which 

 however must have be- 

 longed to the class of 

 Cephalopodous Mollusks, 

 or cuttle-like animals. 

 Atlanta inhabits the Indian 

 seas. [GASTEROPODA.] 



Lesueur describes another 

 marine genus, A flan, which 

 must not be confounded 

 with the above. A tlaa has 

 no shell; and Cuvier con- Atlanta Ptnmi. a, natural *\,x. 



fesses his inability to class it, " so confused," says he, " is the descrip- 

 tion." De Blaiuville thinks that it belongs to the same family as 

 Gaiteroptera, and places it accordingly under Akera, though he con- 

 fesses that it is not entirely known. 



ATLAS, the first vertebra of the neck, so named because it sustains 

 the glob"e of the head. It diners in several important circumstances 

 from all the other vertebra; that enter into the composition of the 

 spinal column, because it has distinct and peculiar offices to perform. 

 It has to support the head, and to allow it the power of exercising two 

 different kinds of motion, namely, a motion forwards and backwards, 

 or that of flexion and extension ; and a rotatory motion, or the power 

 of describing a certain portion of a circle, as it does when it turns from 

 side to side. These motions are accomplished by the peculiar mode 

 in wljich the head is connected to the atlas, and the atlas to the 

 second vertebra of the neck, the Vertebra dentata, or Axis. The head 

 is so united with the atlas as to form a perfect hinge-joint, that is, a 

 joint which admits of flexion and extension, or a motion forwards and 

 backwards. The second vertebra, the dentata, forming a pivot on 

 which the atlas turns, and therefore called axis, is united with the 

 atlas in such a manner as to constitute a perfect rotation-joint, or a 

 joint which admits of a rotatory motion. The head being firmly con- 

 nected with the atlas and carried round with it whenever the latter 

 turns upon its axis, it is plain that by the combination of the two 

 joints, namely, the hinge-joint and the rotation-joint, the head can be 

 moved in every direction forwards, backwards, and from side to side. 

 In the construction of these joints such is the perfection of the 

 mechanism that these combined motions are attained to the utmost 

 extent, and are performed with the greatest ease. The connection of 

 tin! different parts with each other forms a union of amazing 

 strength and security, and at the same time certain organs of extreme 

 delicacy and of vital importance are effectually guarded from injury. 

 [>),/,;/ <'i,l,imn, under .SKELETON.] 



A'TRIPLEX, a genus of plants belonging to the natural ordvr 



ii'iiliiicaf and the tribe Atripliate. It has monoecious rarely 



pi-rfcct flowers, the perigone of two more or less connected parts, two 



Ktigmas, a free membranous pericarp, a crustaceous testa ; the seed is 



vertical, attached by a lateral hiluni, either near the base or by means 



elongated funiculus in the middle of the side ; the radicle basal ; 



Amiens five, continuous. Most of the species of this genus are 



insignificant weeds, and are sometimes troublesome peats in corn-fields. 



Babington, in his ' Manual of British Botany,' enumerates ten species 



HAT. HIST. DIV. VOL. I. 



as inhabitants of Great Britain. The most common forms of the genus 

 on cultivated lands are A. angustifolia, A. erecta, and A. patnla. Mr. 

 Babington has described a new species, which is also found not 

 uncommonly in the United Kingdom. This is A . ddtoidea (Babington) : 

 t has an erect stem with ascending branches ; opposite leaves, all 

 lastate-triangular, with two descending lobes unequally dentate or 

 sinuate-dentate ; the perigone of the fruit ovate-triangular, dentate, 

 tunicated on the back, rather longer than the fruit, collected into a 

 many-flowered, branched, dense panicle ; seeds smooth, shining. 

 A. rosea,A.laciniata,A. littoralis, are frequent plants on the sea-shore. 

 A . prostrata is a coast plant, but is rare in Great Britain, and Babiugton 

 suspects that it may be a maritime form of A. patula, 



A'TROPA, a genus of Dicotyledonous Plants belonging to the 

 atural order Solanacect, and consisting for the most part of poisonous 

 species. It is distinguished from other genera of the same natural 

 order by its regular bell-shaped corolla, its 5-parted permanent 

 calyx, which never acquires a bladdery appearance, and by its succu- 

 lent fruit. 



Atropa Belladonna, Deadly Nightshade, or Dwale, is found nob 

 unfrequently in thickets and hedges in this country. The whole 



Deadly Nightshade (Atropa Belladonna). 



1, A corolla cut open, showing the position of the stamens ; 2, the calyx, 

 with the pistil ; 3, a berry cut in half to show its two cells, in each of which 

 are several seeds. 



plant is of a lightish green colour, except the flowers, which are large 

 and of a dingy brownish purple, and the berries, which are of the 

 rich deep black of black cherries. The root is perennial, the stem 

 grows about 2 feet high, and the leaves are acute, with an oblong 

 figure, tapering to each end. The flowers are bell-shaped, larger than 

 those of the harebell, and placed singly in the bosom of the leaves. 

 The border of the corolla is cut into 5 equal lobes : there are 5 stamens, 

 a tapering pistil with 2 cells, and many seeds in the ovary, a long 

 slender style, and a flattened stigma slightly divided into two lobes. 

 The odour of the whole plant is nauseous and oppressive, as if to warn 

 us of its venomous nature. It is in the leaves, root, and berries that 

 the poison resides, and particularly in the berries, which from their 

 resemblance to cherries have often been eaten by children with fatal 

 consequences. The active property of Belladonna, though most com- 

 monly remarked in the fruit, exists also in the leaves, and especially 

 in the roots, both of which have the same acrid narcotic property. 

 They have nevertheless been frequently employed medicinally, and 

 extract of Belladonna is one of the most energetic preparations in the 

 modern Materia Medica. 



Atropa Mandragora, or Mandrake, is another species still more 

 venomous and dangerous than the last. It is found in many parts of 

 the south of Europe, particularly in the Grecian islands, where it is 

 common. Its root is a large dark-coloured fleshy mass, often divided 

 into two or three forks, which have been fancied to resemble a human 

 body ; this circumstance, and its well-known poisonous qualities, gave 



i 



