436 



IJTDEX. 



OCKL'LI (Latin), minute eyes, 138. 



Oc'topods (Gr. o/cro, eight ; TTOVQ, a 

 foot), animals with eight feet ; 

 the name of the tribe of Cephalo- 

 pods with eight prehensile organs 

 attached to the head. 



CEsoph'agus, the gullet, or tube lead- 

 ing from the inouth to the sto- 

 mach, 345. 



Olfac'tory (Lat. olfactus, the sense 

 of smelling) nerves, 97. 



Ornniv'ora (Lat. omne, all ; voro, I 

 devour), feeding upon all kinds 

 of food, 343. 



Oolite' (Gr. wov, egg ; \i9og, stone), 

 an extensive group of secondary 

 limestones, composed of rounded 

 particles, like the roe or eggs of a 

 fish. 



Oolit'ic formation, 650. 



Oper v culum (Latin, a lid}, applied 

 to the horny or shelly plate 

 which closes certain univalve 

 shells ; also to the covering of 

 the gills in fish, and to the lids 

 of certain eggs. 



Optic lobes, in man, 88. 



Optic nerves, 98, 99, 101. 



Ophid'ians (Gr. 60ic, a serpent), ani- 

 mals of the serpent kind, xxi. 



O'ral (Lat. os, the mouth), belong- 

 ing to the mouth or the speech. 



Orders, a group of the animal king- 

 dom, xx. ; subdivided into families 

 and genera, xx. 



Organism, 36. 



Organized bodies, general properties 

 of, 30 75 ; organized and unor- 

 ganized bodies, 30 34 ; elemen- 

 tary structure of organized bodies, 

 35 56 ; differences between ani- 

 mals and plants, 57 75. 



Ornithichni'tes (Gr. opvig, a bird), 

 the fossil footsteps of birds, 67U 



Orthop'tera (Gr. opQog, straight 

 7TTi.p6v, a wing), the order of in- 

 sects with elytra and longitudi- 

 nally folded wings. 



Os'seous (Lat. os, a bone) tissue, 43. 



Oto'liths (Gr. ovg, an ear ; \i9og, 

 a stone), the stony or chalky bo- 

 dies belonging to the internal ear, 

 156. 



Ova'rium (Lat. ovum, an egg), the 

 organ in which the eggs or their 

 elementary and essential parts are 

 formed. 



Ovary, detachment of the ovum from 

 the, 481. 



Ovig'erous (Lat. ovum, an egg ; gero, 

 I bear), parts containing or sup- 

 porting eggs. 



Ovip'arous (Lat. ovum, an egg ; pario, 

 I bring forth), animals which 

 bring forth eggs, 434. 



Ovo-vivip'arous (Lat. ovum, an egg ; 

 vivus, alive ; pario, I produce), 

 animals which produce living 

 young, hatched in the egg within 

 the body of the parent without 

 any connection with the womb, 

 439. 



OvuUVtion, the production of eggs, 

 437, 438. 



O x vum (Lat. an egg}, detachment from 



the ovary, 481. 



Ox'ygen, quantity consnmedby vari- 

 ous animals, 396*. 



PACHYDER'MATA (Gr. Tra^vq, thick, 

 dfcp/ia,skin),thick-skinned animals, 

 like the elephant, hog, &c., 343. 



Palreontol'ogy (Gr. 7ra\aid'-, an- 

 cient ; ovra, beings ; \6yof, dis- 

 course), the history of ancient ex- 

 tinct organised beings. 



Palreontol'ogy, an essential branch 

 of zoology, 645. 



Palaeozoic age, 658, 659 667. 



Palseothe'rium (Gr. 7ra\, an- 

 cient; 9i]piov, beast), an extinct 

 genus of Pachydermata, 680. 



Pal'lial (Lat. pallium, a cloak), re- 

 lating to the mantle or cloak of 

 the mollusca. 



Palpation, the act of feeling, 175. 



