62 



THE BONES. 



origin of the superior curved lines is very elevated and strong. The cervical tuberosity 

 of the external occipital protuberance is absent or little marked ; the styloid processes 

 are short, and well deserve the name of jugular eminences. The foramen lacerum is 

 divided into two portions by the mastoid protuberance, and the basilar process is wide, 

 long, and thick, and hollowed on the side by a channel that joins a similar one in the 

 temporal bone to form a large venous canal. This last communicates, behind, with the 

 posterior foramen lacerum, and opens, in front, in the cranium, where it is continuous 

 with the cavernous groove of the sphenoid. The anterior angle forms a very marked 

 prominence, which is deeply fixed into the parietal bone, and partly constitutes the 

 internal protuberance of that bone. 



2. Parietal bone. In the Dog the parietal bone, formed by two ossific centres only, 

 is distinguished by the great development of the ridges and the parietal protuberance. 

 This last, constituted in part by the occipital bone, does not show any lateral excavations 

 at its base; they are carried lower, near the summit of the petrous process, on the 

 sides of the occipital bone. The parieto-temporal canals are continued, notwithstanding, 

 to the base of the protuberance, which they traverse, to 

 open into each other in its interior. 



In the Cat there are scarcely any parietal crests, and 

 the internal protuberance is replaced by two great trans- 

 verse bony plates which teparate the cavity of the cerebrum 

 from that of the cerebellum. 



3. Frontal bone. In carnivora, the external face of this 

 bone presents in its middle a more or less marked de- 

 pression. The orbital arch is incomplete, and there is no 

 superciliary foramen, or mortice on the inner face. The 

 bone is united with the supermaxillaries. 



4. Ethmoid bone. The ethmoidal fossa is very deep, 

 and the cells very developed and diverticulated. The per- 

 pendicular lamina is at a late period consolidated with the 

 sphenoid bone. 



5. Sphenoid bone. The superior sphenoid of the Dog is 

 very short, and bears, laterally, two wide wings which 

 ascend to the temporal fossa ; they correspond to those of the 

 sphenoid bone in Man. The inferior sphenoid is, on the 

 contrary, very narrow, and its lateral prolongations, or pro- 

 cesses of Ingrassias, are reduced to very small proportions. 

 The sub-sphenoidal or pterygoid process is very short, and 

 the canal is single, and communicates with the foramen 

 rotundum. The pituitary fossa is shallow, limited behind 

 and before by the posterior clinoid and anterior clinoid 



ANCERIOR processes, so named because of their being compared to the 



four posts of an ancient bed. The supersphenoidal canals 



l,0ccipitaf protuberance; 2, are only two in number : one represents the great spheroidal 

 Median spur of the occi- ? ssure - the t her the round foramen. The carotid notch, 

 pital bone 3 Parietal .j oil " n a similar one in the temporal bone, forms an open- 

 bone- 4 Origin'of the pa- in wnich ma Y be designated the carotid foramen, because 

 rietal crests; 5, Zygomatic jt S^es passage to an extremely remarkable loop the in- 

 process of the temporal ternal carotid artery describes after passing through the 

 bone ; 6, Frontal bone ; 6', car T tid anal - The oval foramen is the same as in the Ox. 

 Orbital process; 7, Zy- In the Ca there is the same disposition with the ex- 

 gorna 8 Lachrymal bone ce P tlon of . no sphenoidal canal or carotid notch beiny: present. 

 9 Nasal' bone -10 Super- 6 - Temporal bone. In the cnrnivora, the articular sur- 

 maxilla- 11 Inferior ori- face of the zygomatic process merely forms a glenoM 

 fice of the supermaxillo- cavit y> into whi( ' h the c..ndyle of the maxillary bone 

 dental canal 12 Pre- exa tly fits. The temporal bone in these animals is also 

 maxillary bone. distinguished by the width of the external auditory canal, 



the absence of a hyoid prolongment, the small development 

 of the mastoid and styloid processes, the enormous volume 



of the mastoid protuberance, and the presence of two particular canals which cannot be 

 traced in the other animals. One of them, the carotid canal, traverses the mastoid 

 portion, and joins, superiorly, the venous canal which passes between the basilar 

 process and the temporal bone ; by its inferior extremity it joins the carotid foramen 

 which itself penetrates the cranium, a little beyond the venous canal just mentioned. 

 The other conduit is pierced in the petrous portion immediately above the carotid canal ; 

 it affords a passage to the fifth pair of encephalic nei ves. 



HEAD 



