MAN. 323 



directly used as weapons of offence and defence, nor in procuring 

 food. The facial * and basicranial axes are not, as in the Kabbit, 

 nearly in the same straight line, but the former is bent sharply 

 downwards, so that the craniofacial angle is not more than 120, 

 and in many races may be much less, 90 being the usual inferior 

 limit. Many of the bones of the skull are very strong and thick, 

 and fusion has taken place to a much larger extent than in the 

 Rabbit, (a) Cranium. The four elements of the occipital ring 

 (basi-, ex-, and supra-occipitals) are united into a single occipital 

 bone, and a median sphenoid bone is formed by the fusion of the 

 ventral portions of the parietal and frontal rings. The sphenoid 

 consists of a central body and two pairs of lateral expansions or 

 " wings." The anterior part of the body = presphenoid, and the 

 posterior part (on the dorsal side of which is the sella turcica for 

 the pituitary body) = basisphenoid. The anterior or lesser wings 

 = orbitosphenoids, and the posterior or greater wings, with which 

 the small pterygoids are fused ventrally, = alisphenoids. The 

 parietals are distinct, but the frontals are usually united together 

 into one bone. The ethmoid bone, which completes the morpho- 

 logically anterior end of the cranium and forms a large part of 

 the bony framework of the olfactory capsules, consists of (a) a 

 small horizontally placed cribriform plate, (ft) a vertical bony plate 

 (lamina perpendicularis), which with its cartilaginous continuation 

 (septum nasi) constitutes a party- wall between the olfactory cap- 

 sules, and (y) two lateral masses of the ethmoid ( = ethmoturbinals) 

 projecting into the capsules. In the auditory- region of the cranium 

 a great deal of fusion has taken place leading to the formation of 

 a large temporal bone = periotic + tympanic + squamosal, which 

 are represented by different regions, as follows : Petrous and 

 mastoid regions = periotic, tympanic plate = tympanic, and 

 squamous region =- squamosal. Besides this, the temporal pos- 

 sesses a prominent styloid process mainly formed by the fusion 

 of two small elements (tympano-hyal and stylo-hyal) belonging to 

 the upper end of the hyoid arch. (b) Face. The olfactory 

 capsules are relatively short and deep. The part taken by the 

 ethmoid in their formation has been mentioned above. Each 

 lateral mass of the ethmoid is divided into upper and lower parts, 

 known as the superior and middle turbinate bones. These are 



* The facial axis is a line joining the front of the premaxilke with the 

 anterior end of the basicranial axis. 



