THE POSTERIOR SURFACE OF THE OCCIPITAL BONE

(AFTER SAPPEY.) ance; 5, the internal o:cipital crest; 6, 6, the cerebral fo æ; 7, 7, the cerebellar fo æ; 8, the foramen magnum; 9, the basilar groove; 11, 11, the posterior condylar foramina; 2, the protuberance; 3, B, the euperior curved lines; 4, the external occipital crest; §, 5, the inferior curved lines; 1, the foramen magnum; %, 9, the posterior 14, the basilar proce . tive anatomy, a b. which is the homologue of the superior turbinated proce of the ethmoid b. in man, [L, 153,|—Navicular b. Lat., 0s naviculare, 1. A sesamoid b. in the tendon of the flexor digitorum rofundus of the solipeds, lying behind the third phalanx. {L, 13.] . See Scaphoid b.—Non-pneumatic. B’s which do not contain air-cells or air-sacs. (L, 204.] Cf. Pneumatic b’s.—Occipital b. Lat., 08 occipitale. Fr., os occipital. Ger., Hinterhauptbein. A rhomboidal b. situated at the lower and back part of the cranium. It is divided into the basilar portion (the bas i occipital), the condylar portions (the ercreanitals and the tabular portion (the supra occipital and the interparietal). ‘The basilar portion, or the occipital [pes projects forward, articulates with the body of the sphenoid , and forms the anterior edge of the foramen magnum; the condylar portions form the lateral margins of the foramen magnum, articulate with the mastoid and petrous portions of the temporal b’s, and bear the occipital condyles; the tabular peiion! [ieee forward to articulate with the parietal and temporal b’s and ears upon its outer surface the superior and inferior curved lines, the external occipital crest, and the external occipital protuberance. At birth this b. consists of four pieces, the bas i occipital, the two exoccipitals, the supra-occipital, and the interparietal, all of which are fused into one piece at about the sixth year. [L, 12, 142, 153.] —Occipito-otic b. A b. ocenpying the occipital and auditory regions in certain of the Anura in an early stage of their development, which subsequently separates into the occipital and prootic b's. [L, 202]-Odontold b. Lat., os odontoideum. The odontoid {pee of the axis when, as in certain animals, it is a separate [L.J|—Olfactory b. 1. See Ethmoid b. 2. See Mes ethmoid b.—Opereular b. _ Lat., operculum. Fr., 0s opercula ire, stapéal (G. St.-Hilaire]. Ger., eigentliches Kiemendeckelstiick, A flat, triangular b. situated at the side of the head, in fishes, which articulates in front with the hyo-mandibular b. and a ists in forming the edge of the gill-cover. |L, 12, 207.|—Opereulo-angular b. See Angular b.—Opisthotie b. A b, of certain of the lower vertebrates which forms the postero-ventral portion of the auditory capsule. In man it is represented by the lower portion of the petrous portion of the temporal b., the fenestra rotunda, and the lower half of the fenestra oval is. [L, 12, 142, 153.|—Orbicular b. Lat., 08 orbiculare. A small disc of b. found in some of the lower vertebrates, attached to the long crus of the incus; represented in man by the orbicular proce of the incus. [L, 142, 200.]— Orbito-sphenoid b. Lat., ala magna sphenoidei (in fishes and reptiles), ala parva sphenoidei (in birds and mammals) [Hallmann]. Fr., aile orbitaire (in fishes, birds. and mammals [Cuvier]), ptéréal fin the crocodile), rocker (in birds) [G. St.-Hilaire]. Ger., gro er $10, 10, the sondpie condyles; 11, the basilar proce ; 14, 14, the jugular proce es. eral wall of the nose between the internal pterygoid plate of the sphenoid b. and the superior maxilla, It consists of a horizontal and a vertical plate, which are united at a right oi and of three proce es, the pyramidal, the orbital, and the nasal. It articulates with its fellow of the opposite side, with the vomer, with the superior maxilla, and with the ethmoid, sphenoid, and inferior turbinated b's. [L,142.] 2. In comparative anatomy, a b, which extends between the pterygoid and maxillary regions. [L, 12, a Palato-maxillary b. In comparative anatomy, a b. formed by