208 Mammalia. 



that it is joined, a little distance anterior to the clavicle, by 

 the anterior jugular vein, which arises from the convergence 

 of some superficial branches in the submaxillary region. 



The further dissection of the Head will be better traced in 

 a larger subject, e.g., the Head of a Sheep, to which we 

 propose to call the attention of the Student for his next 

 dissection. 



lY. THE CEEEBRAL NERYES, &c. 



AS DISSECTED IN THE 



SHEEP'S HEAD. 



General Examination. The Sheep's Head as usually 

 supplied from the market is devoid of skin, and without its 

 external ears ; the junction of the Ear with the Head being 

 indicated by the cartilaginous portion attached to the ex- 

 ternal auditory meatus. 



The occipital condyles stand out clearly, denuded of their 

 connections with the first cervical vertebra or Atlas ; between 

 them is the cut end of the spinal cord, surrounded by its 

 loose sheath of Dura Mater ; loose, that is, around the cord 

 which is much smaller than the sheath ; but attached to the 

 ventral segment of the circumference of the Foramen Mag- 

 num. The cord itself presents in its section the shape of a 

 flattened cylinder, and will be found to be closely invested 

 with a dense white coating, or Neurilemma,* formed by the 

 membrane called Pia Mater ; between this Neurilemma and 

 the sheath of Dura Mater is the cavity enclosed by the 

 delicate, serous, Arachnoid membrane. The section of the 



* Neurilemma, pevpop, a nerve ; Xf/x/^a, a peel or coyering. 



