EXTERNAL CHAEACTERS 305 



one by one, in order that each may be studied in its entirety 

 as far as practicable, and the mutual relations of its several 

 parts demonstrated. This method is the best, and should be 

 followed whenever possible. If, however, it is intended to 

 perform the whole dissection on a single rabbit, it will be 

 found advisable to somewhat modify the order of proceeding. 



For dissection, rabbits should be taken that are not less 

 than six months old, or the reproductive organs will not be fully 

 developed. They may be killed by pouring a few drops of 

 solution of cyanide of potassium into the mouth, or else by 

 chloroform, or by drowning. 



The brain should be removed at once and put into strong 

 spirit. {Seep. 350.) 



I. EXTERNAL CHARACTERS. 



The whole body is covered with hairs, of variable colour ; 

 and is obviously divided into head, neck, trunk, a short taU, 

 and two pairs of limbs. 



A. The Head. 



Note the general form of the kead. Determine the position 

 of the mandible, the zygomatic arches, the supra-orbital pro- 

 cesses of the frontals, and other parts of the skull, by feeling 

 through the skin. 



1. The mouth is a small transverse aperture on the under 



surface of the front of the head, bounded by the soft 

 hairy lips. The upper lip is divided by a median 

 cleft, which connects the mouth with the nostrils, 

 and leaves the upper incisors exposed. 



2. The nostrils are a pair of oblique slits at the end of the 



hairy snout. 



3. The eyes are large, and placed at the sides of the head. 



Each eye is protected by an upper and a lower eye- 

 lid, fringed with scanty eyelashes ; and by a third 

 eyelid, or nictitating membrane, a hairless fold of 

 opaque white skin, which lies within the other eye- 

 lids, and can be pulled across the eyeball from the 

 anterior angle or canthus. 



X 



