Ὄϊς, sheep, Ovis aries, 72; different kinds, 208. Οἶστρος, gad fly, Tabanus corvinus, 3, 9, 83, 89; origin, 125; a blood sucker, 208; the marine species probably refers to certain parasites on fish, Lernæa brachialis, Phalangium balænarum, 135, 208, 212, 219. Οἶστρος, a bird, perhaps Motacilla sibilatrix, or Trochilus, 202. Ὁλοθούριον, probably an alga Spongodium, _Spratt's Lycia_, Holothuria or Salpa, 4. Ὄνος, ass, Equus Asinus, 27, 31, 39, 68, 70; not infested with lice or ticks, 135; reproduction, 113, 163, 171; food and drink, 207; diseases, 224; a foe to the Ægithus, 232; eats thorns, 233. Ὄνος ὁ ἄγριος, the wild ass, 178; in Epirus, 71; the Indian ass, perhaps Rhinoceros, 28. Ὄνος, fish, perhaps Raia squatina, _Strack_, Gadus mustela, 214, 255. Ὄνος, woodlouse, Oniscus asellus, 135. Ὀρεινὸς, a species of titmouse, Parus Ater, 202. Ὀρειπέλαργος, Grypaetus Barbatus, _Strack_, 251. Ὀρεὺς, mule, 5, 11, 27, 31, 39; females and reproduction, 163, 172, 173; food and drink, 207. Ὀρίγανος, plant, Origanum, 238. Ὄρκυς, a large kind of tunny, Scomber ala longa, 109. Ὄρνις, domestic fowl, see ἀλεκτόρις and ἀλεκτρυὼν. Ὄροβος, tares, Orobus, Ervum ervilia, 71, 191. Ὀρόσπιζος, mountain finch, Fringilla montifringilla, _Strack_, 202. Ὀρσοδάκνη, an insect that eats the buds of plants, Chrysomela oleracea, 126. Ὀρτυγομήτρα, perhaps Land rail, Rallus Crex, 210. Ὄρτυξ, quail, Coturnix Vulgaris, 40, 45; nest, 146, 240; migration, 210; does not perch on trees, 242. Ὄρυξ, Nilghau, Antilope picta, or Antilope Oryx, 27. Ὀρφὸς, a sea fish, perhaps Scorpæna porcus, _Spratt's Lycia_, 109, 199, 211, 214. Ὀρχιλος, a bird, Charadrius minor, 232. Ὀστρακόδερμα, testaceous mollusca, 8, 10, 13, 73, 81; reproduction, 110, 115, 117; compared with plants, 195; hybernate, 213; best for food when they have ova, 228. Ὄστρεον, oyster, 3, 10, 117; different kinds, 73; origin, 117; have an anus, 198; τά ὀστρεώδη, testacea, 228. Ὄστρειον, the shell used by painters, 118. Οὖραξ, Otis houbara, 139. Οὖς θαλάττιον, sea ear, perhaps Haliotis, 84. Ὀφίδιον, a small serpent, found in the plant silphium, 227; a small serpent, Coluber ammodytes, or C. Æsculapii, _Strack_, _ib._; an Indian serpent, whose bite is fatal, _ib._ Ὄφις, serpent, 5; winged serpent in Æthiopia, perhaps Draco volans, 9; a horned serpent in Egypt, Coluber cerastes, 28; water-serpents, Coluber natrix, 10, 35, 38, 43, 44, 46, 49, 60; marine serpents, Muræna ophis, or Ammodytes tobianus, _Strack_, 38, 255; there are many kinds. Their hissing, 96; the female larger, 100; reproduction, 103, 137; change their skin, 121, 216; omnivorous, 204; hybernate, 213; a large kind in Lybia, Boa constrictor, 226; the blind serpent, Anguis fragilis, 223.