The alligator and its allies . red in the em-bryo. It is a heayy bone whose dorsal surface isflattened posteriorly, deeply concave in the middleregion, and drawn out into a long projection anteri-orly. It forms part of the roof of the cranialcavity and articulates ventro-laterally with thealisphenoid and anteriorly with the prefrontals andnasals. It forms a part of the median boundary ofthe orbit. The prefrontal (4) is an elongated bone in thelatero-median border of the orbit. Medially andanteriorly it articulates with the frontal and nasal,laterally with the maxillary and lachrymal, andventra
The alligator and its allies . red in the em-bryo. It is a heayy bone whose dorsal surface isflattened posteriorly, deeply concave in the middleregion, and drawn out into a long projection anteri-orly. It forms part of the roof of the cranialcavity and articulates ventro-laterally with thealisphenoid and anteriorly with the prefrontals andnasals. It forms a part of the median boundary ofthe orbit. The prefrontal (4) is an elongated bone in thelatero-median border of the orbit. Medially andanteriorly it articulates with the frontal and nasal,laterally with the maxillary and lachrymal, andventrally, by a heavy process, with the pterygoid. The nasal (25) is a long narrow bone forming thegreater part of the roof of the nasal the median line of the skull it articulateswith its fellow; posteriorly with the frontal;laterally with the prefrontal and maxillary; andanteriorly with the premaxilla. In the crocodile,caiman, and gavial it also articulates with thelachrymal. In the alligator the anterior ends of the. Fig. 19. View of the Skull of theAlligator {A. Mississippiensis). 12. quadratojugal. 23. parietal. 24. frontal. 25. nasal, aw, anterior nares; 1. premaxilla. 2. maxilla. 3. lachrymal. 4. quadrate. 0, orbit; pb, postorbitalbar; sf, supratemporalfossa; //, lateral tem-poral fossa. The Skeleton 6i two nasals form a narrow rod of bone that extendsacross the anterior nares, and, meeting a projectionfrom the premaxillaries, divides the opening intoright and left halves. In the crocodile the nasalsproject only a very little way into the nares; inthe caiman (according to Reynolds) they do notextend into the nares at all, and in the gavial, whosemuch elongated snout is mainly due to the greatlength of the maxillaries, the nasals do not extendmore than a third of the distance from the pre-frontals to the anterior nares. The maxilla (2) is a large bone that forms a largepart of the upper jaw and that holds
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Keywords: ., bookcentury1900, bookdecade1910, bookpublishernewyo, bookyear1915
