ANN 



ANO 



to pieces on the application of violence 

 or a high temperature. 



ANNE'LLIDA {annellus, a little ring). 

 A class of animals which have their 

 bodies formed of a great number of small 

 rings, as the earth-worm. They were 

 distinguished, in Cuvier's arrangement, 

 by their red blood, and by the circulation 

 of their blood in a double system of com- 

 plicated vessels, MM. Audoin and Milne 

 Edwards adopt four divisions, differing 

 in habits and structure : — 



1. Erranlia. Walking or swimming 

 animals, rarely sedentary. Head distinct 

 from the body ; with antennae, eyes, and 

 generally jaws. These are the dorsi- 

 branchia of Cuvier, the nereidce of Sa- 

 vigny. 



2. Tuhicola. Sedentary animals, in- 

 habiting the interior of solid tubes. Head 

 not distinct ; without eyes, antennae, or 

 jaws. 



3. Terricola. Animals furnished with 

 bristles instead of feet ; dwelling in the 

 earth. No distinct head, antennae, or 

 jaws. 



4. Suctoria. Animals without feet or 

 bristles, but furnished at each extremity 

 of the body with a prehensile cavity or 

 sucker. No distinct head; but generally 

 with eyes and jaws. Chiefly parasitic. 



Divisions of Dr. Grant. Dr. Grant 

 divides the Annellida into the following 

 orders, by the differences of their respi- 

 ratory organs : — 



1. Apneumata, or those which have 

 no perceptible respiratory organs, as 

 the nais. 



2. Cephalobranchia, or those which 

 present distinct branchiae at the ce- 

 phalic extremity of the body, as the 

 serpula. 



3. Dorsibranchia, or those which 

 have external or internal branchiae 

 disposed along the back of the trunk, 

 as the nereis. 



4. Pulmonata, or those which breathe 

 by pulmonary sacs, as the lumbricus. 



ANNUAL REVOLUTION. The 

 yearly course of the earth in its orbit 

 round the sun. It must be distinguished 

 from the diurnal motion. The latter 

 produces only day and night ; the former 

 causes the different lengths of day and 

 night, as well as the phenomena of the 

 seasons. 



ANNULAR ECLIPSE {annulus, a 

 ring). A term applied in Astronomy to 

 those eclipses of the sun, in which a ring 

 of light is visible around the dark body 

 of the moon. 



A'NNULATE {annulus, a ring). 

 Ringed; surrounded or marked by rings, 

 as certain vessels in plants ; also certain 

 animals which appear to be composed of 

 a succession of rings. 



ANNULO'SA {annulus, a ring). A de- 

 signation given by Macleay to the divi- 

 sion of animals included in the Articu- 

 lata of Cuvier, the Homogangliata of 

 Owen, and the Diploneura of Grant. 

 Macleay's term relates merely to their 

 annulated skin. 



A'NNULUS. A ring. 1. The geome- 

 trical term for a solid formed by the revo- 

 lution of a circle about a straight line 

 exterior to its circumference, as an axis, 

 and in the plane of the said circle. 2. The 

 term annulus is applied, in Botany, to 

 that part of the theca of ferns, where the 

 stalk is united with its side ; and to the 

 collar which surrounds the stipes in the 

 highest forms of the fungi. 



A'NODE {ava, upwards, 6d6s, a way). 

 A term applied by Mr. Faraday to that 

 part of the surface of a decomposing 

 body which the electric current enters — 

 the part immediately touching the posi- 

 tive pole. See Kathode. 



ANODO'NTINiE (a, priv., hdov^, 

 o36i/Tor, a tooth). A sub-family of the 

 Unionidcs, or River Mussels, named from 

 the genus Anodon, the shell of which 

 has no articular processes, or teeth, at the 

 hinge. 



ANODY'NE {dvM^vvof, without pain). 

 That which relieves from pain. An agent 

 of this kind which induces sleep, is called 

 a hypnotic; if it causes insensibility, it 

 is termed a narcotic. 



ANO'MALI'STIC YEAR {dvcofMaXo?, 

 irregular). The interval which occurs 

 between two consecutive returns of the 

 earth to the perihelion, or its least dis- 

 tance from the sun. The difference be- 

 tween the anomalistic and the tropical or 

 common year is owing to the orbit of the 

 earth representing an ellipse, of which 

 the major axis has a slow motion of 

 11 ".8 per annum in advance. In de- 

 scribing this arc, the earth occupies 

 4' 39". 7, which, being added to the side- 

 real period, gives 365d. 6h. 13m. 49s.3 

 for the anomalistic year. See Tropical 

 Year. 



ANO'MALY {dvu)fxa\o9, irregular). 

 A term applied, in Astronomy, to the 

 angle through which the radius drawn 

 from a planet to the sun has moved with 

 the planet from the time when this was 

 at its least distance from the sun. The 

 mean anomaly is proportioned to the time 

 C3 



