APH 



AP 



the cavity from which trie head of the 

 animal is protruded. 



APE'TALOUS (a, priv., weraXov, a 

 petal). A term applied to plants which 

 have a calyx, but no corolla or petals. 

 They are also called monochlamt/deous, 

 as having a single envelope, viz. a 

 calyx. 



A'PEX. The pointed top of a cone. 

 The point or nucleus of a shell; and 

 hence the term is applied to the bosses 

 of bivalves, the points or tops of limpets, 

 or of univalves. In Botany, the apex of 

 a seed is the extremity opposite to the 

 base ; the apex of a fruit is the part 

 where the remains of the style are 

 found. 



APHiE'RESIS (ciTTo, from, alpeco, to 

 take). Literally, a taking away ; a gram- 

 matical figure by which words are shorn 

 of their fair proportions, as when we say 

 'tis for " it is ;" 'tisn't for " it is not." 



APHANI'PTERA (ucpaviji, obscure, 

 TTTepov, a wing). The Flea tribe ; an 

 order of insects which have only the 

 rudiments of wings, in the form of little 

 scales, attached to the second and third 

 segments of the body, in which there is 

 no proper distinction of thorax and ab- 

 domen. They undergo metamorphosis. 



A'PHANITE (a^ai/J;?, indiscernible). 

 A greenstone rock containing amphibole 

 as its principal ingredient, and named 

 from the indiscernible distinction of its 

 parts. It is the lapis corneus trapezius 

 of the old mineralogists. 



APHE'LION (iTTo, from, hXtot, the 

 sun). An astronomical term, denoting 

 the greatest distance of a planet from the 

 sun. Its opposite point is the perihelion, 

 which is the nearest point to the sun. 

 These two points are, therefore, the two 

 extremities of the greater axis of an 

 orbit. 



A'PHID^ {aphis, the plant-louse). 

 The Plant Lice ; a family of the dimerous 

 Homoptera, which infest plants, and are 

 vulgarly supposed to give rise to the phe- 

 nomena of blights and honey-dew. 



APHLOGI'STIC (ci0A67t(TTO9, not in- 

 flammable). Without flame ; a term ap- 

 plied to a lamp in which the combustion 

 is effected without flame. 



A'PHRITE {dippoi, foam). Earth foam ; 

 a silvery-white, friable carbonate of lime, 

 found in calcareous veins. 



A'PHRIZITE. A variety of black 

 tourmaline. 



APHY'LLOUS (a, priv., 0i',\Xov, a 

 leaf). Leafless ; a term applied to plants 

 which have large scales, but no true 

 33 



leaves ; also to plants in which the true 

 leaves are so small as to be reduced to 

 scales. 



APIA'CEiE {apiiim, parsley). A term 

 recently applied to the family of Umbel- 

 liferous plants, as more consonant with 

 the plan of forming natural orders. See 

 Umbelliferai. 



A'PICAL {apex, the top of a cone). 

 Belonging to the pointed end of a cone- 

 shaped body. 



APIO'CRINITE (ciTTtoi/, a pear, Kplvov, 

 a lily). Pear-encrinite ; a sub-genus of 

 fossil encrinites, in which the stem is 

 rounded and dilated at its upper extre- 

 mity into a pear-shaped figure. 



APIS MUSCA. A modern southern 

 constellation, consisting of four stars. 



APLANA'TIC (a, priv., irXdvn, error). 

 Free from error ; a term applied to those 

 optical instruments in which the spheri- 

 cal and the chromatic aberrations are 

 completely corrected. This term is more 

 correct than achromatic, which merely 

 implies correction of the chromatic ab- 

 erration ; whereas a good, or aplanatic, 

 instrument has its errors of sphericity 

 balanced equally with those of colour. 



APLO'ME (aTrXoof, simple). A mine- 

 ral usually considered as a variety of the 

 garnet, from which, however, it appears 

 to differ in its primitive form. It crys- 

 tallizes in rhombic dodecahedrons, de- 

 rived by the simplest laws of decrement 

 from the cube. 



APOCA'RPOUS (aTTo, from, KdpTroc, 

 fruit). A term applied, in Botany, to 

 that condition of the carpels, in which 

 they are distinct from one another, or 

 easily separable, as in ranunculaceous 

 plants. See Syncarpous. 



APOCY'NACE^. An order of Dico- 

 tyledonous plants, named from the typical 

 genus Apocynum, and agreeing with 

 Asclepiadaceae, but of rather more sus- 

 picious properties. Trees or shrubs 

 usually milky, with leaves opposite, some- 

 times whorled ; corolla monopetalous, 

 hypogynous; stamens inserted into the 

 corolla ; ovaries two ; fruit a follicle, 

 capsule, drupe, or berry, single or double. 



A'PODA (a, priv., irovi, 7ro36s, a foot). 

 An order of Amphibious animals, com- 

 prising only one genus, the Ccecilia, of a 

 serpent-like form, and altogether desti- 

 tute of feet. The term is also applied to 

 an order of fishes which have no ventral 

 fins. See Malacopterygii. 



APO'DOSIS (u7r6doo-49, a giving back). 

 A term employed in Rhetoric to denote 

 the consequent proposition, as opposed to 

 C5 



