THE RABBIT 433 



passes through a separate opening, the foramen rotundum. (8) The 

 foramen lacerum medium, an irregular opening on the under side of the 

 skull between the alisphenoid and the periotic. Its anterior part 

 represents the foramen ovale of other mammals and transmits the 

 mandibular branch of the fifth nerve. (9) The stylomastoid foramen, a 

 small opening behind the tympanic, through which the seventh nerve 

 leaves the skull. (10) The foramen lacerum posterius, an irregular 

 opening on the under side of the skull, between the occipital condyle 

 and the tympanic bulla, through which the ninth, tenth, and eleventh 

 nerves and the internal jugular vein pass, (n) The carotid foramen, 

 which pierces the tympanic bone near its inner border, close to the 

 occipital condyle, and transmits the internal carotid artery. (12) The 

 condylar foramina, a couple of holes in the exoccipital, just in front of 

 the condyle, through which the hypoglossal nerve passes in two 

 divisions. In connection with the tympanic cavity there are two open- 

 ings, the Eustachian canal at the 

 anterior and inner angle of the 

 tympanic bone, on the under side 

 of the skull, behind the foramen 

 lacerum medium, and the external _ 



auditory aperture at the end of the 

 neck or spout of the tympanic flask. 



p.C.-~ 



The shoulder girdle practi- 



„ . cally consists of one 

 Fore-limb. 1.1 1 



bone, the scapula, 



on each side. This is a flat, FlG 7- _ The h id bone ~ of 



triangular structure, with the a rabbiti from above . 



apex downwards and forwards, „ , ., . . , 



r . ' a.c, Ease of the anterior cornu ; b., 



and bears a prominent external body ;p.c, posterior cornu. 



ridge or spine, which at its 



lower end becomes free as an acromion with a long back- 

 ward metacromion. At the apex is the shallow glenoid 

 cavity for the humerus, in front of which a small hook or 

 coracoid process represents the coracoid bone of the frog. 

 Along the convex dorsal border lies a narrow cartilaginous 

 suprascapula. The clavicle is a slender, curved bone, lying 

 in a ligament between the acromion and the sternum. In 

 mammals which move the forearm freely, as in man, it is 

 well developed and articulates with acromion and sternum. 

 The hip girdle is large, and each of its halves is known 

 as an os innominatum or coxce. With the sacrum it forms a 

 ring called the pelvis. In each os coxse may be recognised 

 a large dorsal ilium articulated with the sacrum, a posterior 

 ischium, and a smaller, ventral and anterior pubis which 



