140 



ANIMAL BIOLOGY. 



[Part I. 



bear the same relation to the brain-case, shown in Fig. 44, B. 

 The jaw-apparatus bounds the mouth in the antero-lateral region. 

 We will consider the skull under the following heads : (1) 

 brain-case, (2) olfactory chamber, (3) auditory chamber, (4) 

 optic chamber, (5) maxillary region, (6) mandible, (7) hyoid. 1 



(A.) The Rabbit's Skull. (1.) Brain-case (Figs. 44 A. and 45). 

 The posterior wall of the brain-case is formed, in the adult 



iG. 44. SKULL OP RABBIT. 



A. Diagrammatic section. B. Diagram to show relation of sense capsules 

 to brain-case. C. Periotic mass. D. Hyoid. 



In A. a. s. Ali-sphenoid. 6. o. Basi-occipital. ft.s. Basi-splienoid. cr. Cri- 

 briform plate, e. o. Ex-occipital. /. m. Foramen magnum, fl. Floccular 

 fossa, fr. Frontal, i. pa. Inter-parietal, o. s. Orbito-sphenoid. pa. Parietal. 

 p. s. Pre-sphenoid. per. Periotic. s. o. Supra-occipital, s. t. Sella turcica. 

 sq. Squamosal. 1-9. Foramina. 



In B. au. Auditory capsule, ol. Olfactory capsule, op. Optic capsule. 



In C. /. o. Fenestra ovalis. /. r. Fenestra rotunda, ep.o. Epiotic. op.o. 

 Opisthotic. pr.o. Prootic. 



In D. a. c. Anterior cornu. p. c. Posterior cornu. bh. Basi-hyal. 



rabbit, of a single bone (the occipital) pierced by a large hole, the 

 foramen magnum (9. /. m.), through which passes the spinal cord. 



1 The student should prepare a young and an adult skull, with all the bones in 

 their natural connection. This is best done by dissecting away the muscle, 

 and carefully scooping out the brain, dipping the skull occasionally in boiling 

 water for &few minutes. A young skull should also be left in water to macerate 

 for a week or two. The several bones will then readily separate. They should 



