ORNITHOID 



247 



ORTHOTROPOUS 



Ornithoid, (or'ni-thoid). [Gk. ornis, bird; 



eidos, form.] Bird -like animals, known 



only by fossil footmarks and other tracks. 



v. Lithichnozoa. 0. hzards=0. Batrachians. 



0. marsupmlia=:A.nomsep\is. 

 Ornithology, (or-ni-thol'o-j i). [Gk. ornis, bird ; 



logos, discourse.] The division of the science 



of zoology which relates to birds. 

 Ornithopus, (or-nith'o-pus). [Gk. ornis, bird; 



pous, foot.] 1. Bird's-foot trefoil: an herb, 



belonging to Fabacese, named from the form 



of the fruits. 2. A bird, known only by 



fossil footmarks, v. Lithichnozoa. 

 Ornithorhynchus, (or-nith-6-ring'kus). [Gk. 



ornis, bird; rygchos, beak.] =Duck- billed 



Platypus = Water - mole = Duck - mole : an 



aquatic animal, found in Australia, having 



the form of a quadruped, covered with hair, 



having spurs like a fowl, and a mouth like 



the beak of a duck: graduates towards rep- 



tiles. 

 Ornithosauria, (or - nith - 5 - saw ' ri - a). [Gk. 



ornis, bird : saura, lizard.] = Pterosauria: 



reptiles related to birds ; regarded as a 



primary division of Vertebrata. 

 Ornithotomy, (or-nith-ot'o-mi). [Gk. ornis, 



bird; tome, section. ]=. Anatomy of birds, v. 



Zootomy. 

 Ornus, (or'nus). [The Latin name.] Flowering- 



ash: a plant belonging to Oleacese. 0. rotun- 



<fi/0Jia=Manna-ash. 

 Orobanchaceee, ( or - 6 - bang - ka'se - e ). [Oro- 



banche.]= Broom -rapes: leafless herbs, para- 



sitic upon roots, belonging to Gentiariales. 

 Orobanche, (or-5-bang'ke)) [Gk. orobos, vetch; 



agcho, I strangle.]=Broom-rape: the type of 



Orobanchacese, q.v. 

 Orontiacese,(or-on-ti-a'se-S):=Orontiads: herbs, 



some stemless, with broad leaves, belonging 



to Juncales. 

 Orobus, (or'o-bus). [Gk. oro, I stimulate; 



boos, ox. ]=Bitter- vetch: a plant belonging 



to Leguminacece. 

 Orographical, (5 - r5 - graf ' i - kal). [Gk. oros, 



mountain; grapho, I write.] Eclating to 



the description of mountains. 0. map= 



Map of mountainous districts. 

 Orphanozoa, (or-fan-o-zo'a). [Gk. orphanos, 



orphan; zoon, animal.] Ehrenberg's term 



for Amphibia and fishes, which take no care 



of their young. 

 Orphean warbler=Sylvia orphea: a song bird 



belonging to Insessores; rare in England. 

 Orpiment, (or'pi-ment). [L. aim, of gold; 



pigmenlum, paint.] = Yellow sulphide of 



=As2S3: used for colouring: a yellow, 



translucent mineral, crystallising in rhombs, 



belonging to the arsenic group. 

 Orpine, (or'pin)^Sedum: a succulent herb 



belonging to Crassulacese. 

 Orrery, (or're-ri). [The Earl of Orrery.] An 



apparatus for showing the relative sizes, 



motions, and positions of the sun and 



planets, including the earth. 

 Orris, (or'ris). [Corruption of Iris. ]=Iris, q.v. 

 Orsellic acid, (or-sel'lik). [Orsella, a lichen.] 



=Lecanpric acid, q.v. 

 Orthagorisca, (or-tha-go-ris'ka). O. mola= 



Molebut: a variety of the sunfish. 



Orthidse, (or'thi-de). Orthis, q.v. ; eidos, 



form.] A family of molluscs, belonging to 

 Brachiopoda. 



Orthis, (or'this). [Gk, orthos, straight.] A 

 genus of Brachiopoda: found fossil, very 

 abundantly, in Silurian rocks. 



Orthite, (or'thit). [Gk. orthos, straight.] A 

 brittle mineral, chiefly silicate of aluminum, 

 iron, &c. ; also called Allanite. 



Orthocephali, (or-tho-sef'a-li). [Gk. orthos, 

 straight ; kephale, head.] = Middle-headed: 

 having the breadth of the head 4ths of the 

 length. cf. Dolichocephalic and brachy- 

 cephalic. 



Orthoceras, ( or-tho'ser-as ). [Gk. orthos, 

 straight; keras, horn .] A cephalopod, charac- 

 teristic of Llandeilo-flag rocks: named from 

 its form. 



Orthoclase, (or-tho'klaz). [Gk. orthos, straight; 

 klasis, fracture.] A transparent mineral, of 

 which there are many varieties, belonging 

 to the felspar group, found in granite, 

 gneiss, &c. : chiefly silicate of aluminum and 

 potassium. Obsidian, pitchstone, porphyry, 

 trachyte, are varieties of O. v. Hardness 

 and Fusibility. 



Orthoclastic, (or-tho-klas'tik). [Gk. orthos, 

 straight; Stasis, fracture.] O. minerals have 

 right-angled cleavage. 



Orthogonal, ( or-thog'on-al ). [Gk. orthos, 

 right; gonia, angle,] Perpendicular: right- 

 angled. 0. system: two surfaces belonging 

 to this system when the principal tangents 

 correspond. 



Orthographic, (or-tho-grafik). [Gk. orthos, 

 correct; grapho, I write.] 0. projection: v. 

 Projection. 



Orthophosphates. v. Phosphates. 



Orthophosphoric acid, (or-tho-fos-for'ik). [Gk. 

 orthos, right; Phosphoric, q.v.] = H^PO^^= 

 Ordinary phosphoric acid=Tribasic P. A.= 

 Trihydric phosphate. 



Orthoptera, (or-thop'ter-a). [Gk. orthos, 

 straight; pteron, wing.] Cockroaches, grass- 

 hoppers, &c.: terrestrial, voracious, herbi- 

 vorous insects, undergoing incomplete meta- 

 morphosis, forming a primary division of 

 insects : have soft leathery elytra, cannot 

 fold the wings crossways. The males are all 

 musical. 



Classification ofO. 



Cursoria=Ruimers. 

 Raptoria= Snatch ers. 

 Ambulatoria=Walkers. 

 Saltatoria= Jumpers. 



Orthorhombic, (or-tho-rom'bic). [Gk. orthos, 

 straight; Rhombus, q.v.] 0. system: in 

 mineralogy = Rectangular system = Pris- 

 matic=Trimetfic: in which the three axes 

 are unequal, and intersect at right angles. 



Orthorhynchus, (or-tlio-ring'kus). [Gk. orthos, 

 straight; rhyychos, beak.] Giant humming- 

 bird ; a sparrow-like bird. v. Trochilidse. 



Orthose=Orthoclase, q.v. 



Orthosilicates. v. Silicates. 



Orthostichies, (or-tho-stik'i-ez). [Gk. orthos, 

 straight; stichos, row.] Straight-rows. 



Orthotropous, (or-thot'ro-pus). [Gk. orthos, 



