276 



SKELETON OF THE EABBIT 



The bones of the cranium proper are arranged in 

 a series of segments or rings, one in front of the 

 other : of these the hindmost or occipital segment 

 is the most obvious, and is very readily detached from 

 the rest of the skull as a bony ring. 



Care must be taken not to confuse these segments 

 with vertebrae, with which they do not correspond. 



a. The occipital segment consists entirely of cartilage - 



bones, which may fuse together inseparably. 



i. The basi-occipital is a median flat bone, forming 



the floor of the hinder end of the cranial 



cavity. It forms the ventral boundary of 



F.M. B.O. B.S. ptA. 



Fig. 58. — lepus cnniculus. The skull from the right side. The middle 

 portion of the zygomatic arch and the right half of the mandible 

 have been removed, (a. m. m.) 



A, external pterygoid process of ali-sphenoid. AS, all-sphenoid. B, interna! 

 orbital foramen. BO> basi-occipital. BS, basi-sphenoid. C, occipital condyle. D, 

 mandibular symphysis. EO, ex-occipltal. F, frontal. FA, foramen lacerum 

 anterius. FM, foramen lacerum medium. G-, orbital groove, for ophthalmic 

 division of trigeminal nerve. I, anterior upper incisor. IF, infra-orbital 

 foramen. IP, inter-parietal. J, lower incisor. L, laorjmal bone. LP, 

 lacrymal foramen. M, maxilla. MIT, mandible. U, nasal bone. OF, optic 

 foramen. OS, orbito-sphenoid. F, parietal. PE, par-occipital process of 

 ex-occipital. PL, palatine bone. PM, pre-maxilla. PO, periotic. PT, 

 pterygoid. S, squamosal. SF, stylo-mastoid foramen. SO, supra-occipital. 

 T, tympanic bone. ZM, zygomatic process of maxilla, cut short. ZS, zygo- 

 matic process of squamosal, cut short. 



