OPI- 



217 



ORD- 



opisthe, behind ; koilos, hollow.] 

 Having the centrum concave be- 

 hind ; appl. vertebrae (anat.}. 



opisthodetic (opis'thodgfik) a. [Gk. 

 opisthe, behind ; detos, bound.] 

 Lying posterior to the beak ; appl. 

 ligaments in some bivalve shells 

 (zool.}. 



opisthoglossal(6pis'th6gl6s'al)0. [Gk. 

 opisthe, behind ; glossa, tongue.] 

 Having the tongue fixed in front, 

 free behind (zool^. 



opisthognathous (opis'thognath'us) a. 

 [Gk. opisthe, behind ; gnathos, jaw.] 

 Having retreating jaws (zool.}. 



opisthotic (op'isthot'ik) a. [Gk. 

 opisthe, behind ; ous, the ear.] 

 Pert, the inferior posterior bony 

 element of the otic capsule (zool.}. 



opisthure (5p'isthur / ) n. [Gk. opisthe, 

 behind ; aura, a tail.] The pro- 

 jecting tip of the vertebral column 

 (zool.}. 



opponens (opo'nenz) a. [L. opponere, 

 to oppose.] Pert, muscles which 

 cause the digits to approach one 

 another (anat.}. 



opposite (op'ozit) a. [L. opponere, to 

 oppose.] Pert, leaves which are 

 opposed, or placed opposite one 

 another at the same level on 

 opposite sides of the stem (bot.} 



opsonic (6pson'ik).0. [Gk. 

 to cater.] Pert, or affected 

 opsonin (phys}. 



opsonln (opso'nln) n. [Gk. 



to cater.] A constituent of blood 

 which helps the phagocytes to de- 

 stroy invading bacteria (phys.). 



optic (6p'tik) a. [Gk. opsis, sight.] 

 Pert, vision. 



optic lobes, that part of the brain 

 which supplies the eyes. 



optic thalami, see thalami. 



opticociliary (Sp'tlkc'sil'ian) a. [Gk. 

 opsis, sight ; L. cilia, eyelashes.] 

 Pert, optic and ciliary nerves (anat.). 



opticopupillary (Sp'tikopu'pilarl) a. 

 [Gk. opsis, sight ; L. pupilla, pupil 

 of eye.] Pert, optic nerve and pupil 

 (anat.}. . 



optimum (op'tlmum) n. [L. optimus, 

 best.] The most suitable degree 

 of heat, etc., for the full develop- 

 ment of the organism concerned 

 (biol.) ; the point at which the best 

 response can be obtained (phys.}. 



optocoel (8p'tosel) n. [Gk. opsis, 

 sight ; koilos, hollow.] The cavity 

 in the optic lobes of the brain 

 (anat.). 



optogram (Sp'togram) n. [Gk. opsis, 

 sight 5 graphein, to write.] The 

 image impressed on the retina by 

 the action of light on the visual 

 purple (phys.). 



ora serrata, the wavy border of the 

 retina, where the nervous elements 

 cease (anat.). 



oral (6'ral) a. [L. os, mouth.] Pert. 

 or belonging to the mouth ; on the 

 side on which the mouth lies. 



orbicular (orbik'ular) a. [Gk. orbis, an 

 orb.] Appl. the eye muscles (anat.}. 



orbicularis (orblk'iila'ris) a. [L. orbis, 

 an orb.] Appl. a muscle whose 

 fibres surround an opening (anat.). 



orbiculate (orbik'ulat) a. [L. orbis, 

 orb.] Nearly circular, in outline ; 

 appl. leaves (bot.). 



orbit (or'blt) n. [L. orbita, a circuit.] 

 The bony cavity in which the eye 

 is situated (anat.) ; the skin round 

 the eye of a bird ; the hollow in 

 the arthropod cephalothorax in 

 which the eye-stalk rises (zool.}. 



orbit*! (or'bital) a. [L. orbita, cir- 

 -it.] Pert, the orbit. 



(or'bitoma'lar) a. [L. 

 circuit ; mala, the cheek.] 

 orbit and malar bone (anat}. 

 *orbitonasal (drTrftona'zal) a. [L. 

 orbita, circuit ; nasus, nose.] Pert. 

 the orbit and the nasal portions of 

 the adjoining bones (anat.). 



orbitosphenoid (6r / blt6sfe'noid) a. 

 [L. orbita, circuit ; Gk. sphen, a 

 wedge ; eidos, form.] Pert, paired 

 cranial elements lying between 

 presphenoid and frontal (zool.). 



order (dr'der) n. [L. ordo, order.] 

 Any group of organisms closely 

 allied, ranking between the family 

 and the class (biol.). 



ordinate (o/dinat) a. [L. ordo, order.] 

 Having the markings or orna- 

 mentation arranged in rows (zool.). 



ordinatopunctate (or'dlna'topungTctat) 

 a. \L. ordo, order ; punctum, 

 a prick.] Indicating the serial 

 presence of dots, etc. (zool.). 



Ordovician (dr'dOvIsh'an) a. [L. 

 Ordovices, people of Wales.] Lower 

 Silurian (pal.). 



