398 THE ANATOMY OF VERTEBRATED ANIMALS. 



two transverse ridges, a third being present, in some genera, 

 on the last inferior molar. 



All the Cynomorpha have ischial callosities, which some- 

 times attain a very large size, and are brightly colored. 



The dorso-lumbar region of the spinal column is concave 

 toward the ventral aspect, and the lumbo-sacral angle is very 

 large. The atlas has narrow transverse processes. The or- 

 dinary number of dorso lumbar vertebrae is nineteen, of which 

 twelve, or thirteen, are dorsal; and seven, or six, lumbar. 

 The middle cervical vertebrae have short spines, which are not 

 bifurcated at their extremities. In the posterior dorsal and 

 anterior lumbar vertebrae, the mammillary and accessory pro- 

 cesses may be enlarged and interlock. The long transverse 

 processes of the lumbar vertebrae bend forward. The sacrum 

 usually contains only three anchylosed vertebrae. The caudal 

 vertebrae vary in number, from three in loiiius (where they 

 form little more than a coccyx), to as many as thirty-one. In 

 the anterior part of the tail the vertebrae are provided with 

 subvortebral, or chevron, bones. 



The thorax is laterally compressed, and the manubrium of 

 the sternum is broad ; but the six or seven sternebrae which 

 follow it are compressed and constricted. 



The skull presents a considerable range of variation. In 

 the Semnojntheci and Colobi^ the frontal region is rounded, 

 the facial angle is comjDaratively large, and the ascending por- 

 tion of the ramus of the mandible is high. In the Macaci and 

 CynocepJiali^ on the other hand, the supra-orbital ridges be- 

 come so much enlarged as to hide the forehead ; and the hori- 

 zontal portion of the ramus of the mandible is much larger 

 than the ascending portion, in accordance wdth the great pro- 

 duction of the upper jaw, and the consequent low facial angle. 

 In many of the Cynocephall^ longitudinal osseous ridges are 

 developed upon the maxillse, and greatly increase the brutish- 

 ness of their aspect. Sagittal and lambdoidal crests may ap- 

 pear along the lines of the corresponding sutures. There is 

 no distinct mastoid process ; and the styloid process is not 

 ossified. The parietal bones do not unite Vvith the alisphe- 

 noids, being separated from them by the union of the squamo- 

 sals with the frontals. The brain-case is flattened and elon- 

 gated, and the convex roofs of the orbits project into it, and 

 greatly diminish the capacity of its frontal portion. The olfao- 

 torj'- fossae are very deep, and sometimes almost tubular. The 

 two frontal bones send thick processes across the base of the 

 skull, which unite over the junction of the presphenoid and 



