The alligator and its allies . he atlas differs from those followingmainly in having a much wider (in an antero-pos-terior direction) neural spine. The lateral pro-cesses and those bearing the prezygapophyses arealso less strongly developed than on the followingvertebrae. The Thoracic Vertebrce. The first thoracic verte-bra differs scarcely at all from the ninth cervical;and the tenth thoracic differs from the first lumbaronly in bearing a short rib. Only the first threethoracic centra bear the hypapophyses noted inconnection with the cervical vertebrae. The ribsof the first two thoracic verte
The alligator and its allies . he atlas differs from those followingmainly in having a much wider (in an antero-pos-terior direction) neural spine. The lateral pro-cesses and those bearing the prezygapophyses arealso less strongly developed than on the followingvertebrae. The Thoracic Vertebrce. The first thoracic verte-bra differs scarcely at all from the ninth cervical;and the tenth thoracic differs from the first lumbaronly in bearing a short rib. Only the first threethoracic centra bear the hypapophyses noted inconnection with the cervical vertebrae. The ribsof the first two thoracic vertebrce articulate withthem by two processes, as in the typical cervicalvertebrae; the other ribs articulate only with thetransverse process. The fourth thoracic may be The Skeleton 55 described as a type of this region (Fig. i8, A). Itscentrum is rather longer than in the first twothoracic and in the cervical vertebrae and has noprocess for articulation with the head of the rib,otherwise it is essentially the same. Like all of B. Fig. i8. Anterior View of A, a Late Thoracic and B, theFirst Sacral Vertebra of a Young Crocodile (C. palustris). X^. (After Reynolds.) 1. neural spine. 4. saeral rib. 2. process bearing prezygapophysis. 5. surface which is united with 3. facet for articulation with the the ilium. capitulum of the rib. 6. concaveanterior face of centrum. the vertebrae behind it and unlike those in frontit is apparently completely fused with its neuralarch. The neural arch is very broad (in an antero-posterior direction) and is extended dorsally as awide neural spine (i). The neural spines of thefollowing thoracic and the first two or three lumbarvertebras are increasingly broad and transverse processes are very broad, long andthin, and in the third to eighth vertebrae they have 56 The Alligator and Its Allies two articular surfaces, an anterior and more medialone for articulation with the head of the rib (3) anda posterior and more distal one for articulati
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Keywords: ., bookcentury1900, bookdecade1910, bookpublishernewyo, bookyear1915
