USED IN NATURAL HISTORY. 



19 



Those of one class especially are 

 named metanwrphic, because they 

 are supposed to have undergone 

 a remarkable change in the course 

 of their formation. From being 

 found invariably in strata or lay 

 ers, aqueous rocks are also termed 

 stratified. 



AQ.XTILA. Lat. An eagle. 



AQ.UILI'ITA. Lat. Of or like an 

 eagle ; rapacious. 



ARA. 7 Systematic names of a 



ARACARI. 5 maccaw. 



ARACH'JTIDA (arak'-ne-da). fr. gr 

 arachne, a spider. A class of ar- 

 ticulated animals. 



ARACH'NID^. Plur. of arachnida. 



AHACH'NIDANS. 7 Animals of the 



ARACH'NIDES. 5 class arachnida 



ARANE'IDA (Plur. arane'idae). fr 



lat. aranea, a spider. A tribe of 



.pulmonary arach'nidans. 



ARACH'NOID. fr. gr. arakne, a spi- 

 der's web; eidos, resemblance. Re- 

 sembling a spider's web. A thin, 

 transparent membrane, which co- 

 vers the brain. 



ARAUCA'RIA. (From Jlrauco, a dis- 

 trict of Chile.) Fir-trees with 

 very rigid branches, having leaves 

 like scales, either small and sharp- 

 pointed, or stiff", spreading, and 

 lanceolate. The Norfolk island 

 pine is one of this genus. 



AR'BOR. Lat. A tree. 



ARBORE'A. Lat. Belonging or re- 

 lating to a tree ; branched like a 

 tree. 



ARBO'REOUS. Being a tree, as dis- 

 tinguished from frutescent or 

 shrubby. 



ARBORE'SCEJTT. fr. lat. arbor, a tree. 



Branching like a tree. 

 AR'CA. Lat. An ark or coffer. 

 Systematic name of certain mol- 

 lusks. 



AR'C^E (ar-kay}. Plur. of Area. 

 ARCHES OF THE BRANCHIAE. A sys- 

 tem of small bones joined toge- 

 ther by ligaments, which sup- 

 ports a series of pectiniform vas- 

 cular fringes, constituting the gills 



of fishes. The branchial arches 

 which are generally four in num- 

 ber on each side, are attached by- 

 one extremity to an intermediate 

 chain of bones, situated in the 

 middle line behind the hyoid 

 bone, while by their opposite ex- 

 tremity they are connected by 

 ligaments to the under surface of 

 the cranium. They are perfectly 

 flexible, and so arranged as to 

 prevent food, taken into the mouth, 

 from being forced out through the 

 branchial fissures with the issiP 

 ing streams of water; so that in 

 reality, these pieces fulfil in their 

 way, the same office as the epi- 

 glottis of mammals. 



ARCHIPE'LAGO. fr. gr. arche, begin- 

 ning; pelagos, sea. An extent of 

 sea sprinkled with islands. 



ARC'TOS. Gr. A Bear. 



ARC'TOMTS. fr. gr. arctos, a bear; 

 mus, a mouse. The marmot. 



ARC'XTATE. fr. lat. arcuo, I bend like 

 a bow. Bent like a bow ; bow- 

 shaped. 



ARCUA'TA. Lat. Arched; bent like 

 a bow. 



ARDEA. Lat. ' A heron. 



A'REA OF SUBSIDENCE. A geological 

 expression used to designate a 

 space which has settled. 



AREXA'CEOUS. fr. lat. arena, sand. 

 Sandy; of the nature of sand. 



ARENA'RIUS. Lat. Growing in 

 sand. 



ARENTICO'LA (Plur. arenicolae). fr. 

 lat. arena, sand ; co/o, I inhabit. 

 A genus of annellidans. 



ARE'OLA. A small area or circle. 

 E'OL^. Little spaces or areas. 



ARE'OLATE. Divided into small 

 spaces, as applied to surfaces. 



AROALI. A wild ram. 



ARGENTI'FEROUS. fr. lat. argentum, 

 silver ; /ero, I bear. Containing 

 silver. 



ARGIL. fr. lat. argttla, clay, formed 

 fr. gr. argos, white ; because when 

 pure, it is white. Old name of 

 alu'mina. 



