90 



THE BONES. 



On the cranium of the Mastiff (a), the parietal bulgings are httle marked ; 

 the parietal crests are very elevated, and join each other early, so that the 

 temporal muscles are in contact throughout the greater part of their inner 

 margin. In the little Lap-dog (d), the parietal crests are widely separated from 

 one another, and the cranium is so very convex as to resemble that of a Monkey. 

 Between these extremes are many intermediates (b, c) ; and it would appear 

 that the development of intelligence in the Dog results in rendering the parietal 

 bones more convex, and the temporal fossEe narrower. 



Comparison of the Head of Man with that op the Domesticated Animals. 



Fig. 5+. 



1. Occipital bone. — The occipital of Man is large, flat, incurvated like a shell, and the ex- 

 ternal tuberosity is slightly developed, aud united by a ridge to the occipital t'oramen, which 



is relatively very wide. Two series of ridges arise from 

 the external tuberosity and pass towards the circum- 

 ference of the bone ; these are the superior and inferior 

 curved or semicircular lines. There is an anterior and 

 a [losterior condyloid fossa pierced by a foramen at tlie 

 bottom; and the jugular eminences, wide and slightly 

 prominent, replace the styloid processes of the domesti- 

 cated animals. 



The internal face of the occipital of Man corresponds 

 with the cerebrum and cerebellum ; and for this purpose 

 it shows four fossae, distinguisiied into superior or cerebral, 

 and inferior or cerebellar. TJiese fossfe are separated by 

 a crucial projection wiioise most developed portion forma 

 the internal occipital protuberance. 



The union of the occipital with the parietal bones, con- 

 stitutes the liimhdoidal suture. At the point where this 

 bone meets the parietal and the squamous portinn of the 

 temporal, is found, in the infant, the lateral posterior 

 fontanel. 



2. Parietal bones. — The parietals are always isolated 

 in early life, aud sometimes consolidated with each other 

 at the adult age. They are very large, quadrilateral, 

 and occupy the summit and sides of the cranium. 



The parietal crests are absent, but are replaced, in 

 certain individuals, by two faintly marked curved lines 

 situated a little above the inferior border of the bone. 

 The middle portion of the external face is very convex. 



On the internal face there is no i)arietal protuberance, 

 but in its stead the internal occipital tuberosity. It 

 also exhibits ramous channels, which in disposition are 

 analogous to the ribs of a fig-leaf ; as well as the parietal 

 fossa, which corresponds to the parietal eminence. 



3. Frontal bone. — The frontal bone of Man forms the 

 upper part of the face and the anterior portion of the 

 cranium. Convex from behind forward, then vertical in 

 its upper three-fourths, the bone suddenly bends at the 

 orbit.s, so as to become horizontal in its lower fourth. 



The external face offers, above tlie forehead, two Literal 

 frontal eminences, and above the nose, a middle frontal 

 boss. To the right and left of the latter are two salient 

 arches — the supra-orbital ridges. The internal face entirely belongs to the cranial cavity. It 

 offers, on the median line, the saggital groove terminated by a frontnl crest; and on each 

 side of this line the frontal fossae, corresponding to the eminences of that name, and orbital 

 bosses to match the orbital roofs. There is no mortise for the articulation of the sphenoid bone. 

 On the middle portion of the superior frontal border, in young persons, is the anterior 

 angle of the anterior fontanel. The anterior border exhibits three supra-orbital foramina 

 and the orbital archei. 



front view of the human 

 cranium. 



1, Frontal bone ; 2, nasal tuberosity ; 

 3, supra-orbital ridge ; 4, optic 

 foramen ; 5, sphenoidal fissure ; 

 6, spheno-maxillary fissure ; 7, 

 lachrvmal fossa ; 8, opening of 

 the nose divided by the vomer; 9, 

 infra-orbital foramen ; 10, malar 

 bone ; 11, symphysis of the lower 

 jaw; 12, mental foramen; 13, 

 ramus of the lower jaw ; 14, parie- 

 tal bone; 15, coronal suture; 16, 

 temporal bone ; 17, squamous 

 suture ; 18, upper part of the great 

 ala of the sphenoid bone; 19, com- 

 mencement of the temporal ridge ; 

 20, zygoma of the temporal bone 

 concurring to form the temporal 

 arch ; 21, mastoid process. 



