Chap. III.] GENERAL ANATOMY. 37 



8. The urinary bladder (13, V. B.) opens on the antero-ventral 

 side of the ureter. 



9. The posterior nares do not open into the mouth, nor are 

 there any Eustachian tubes. 



10. Respiration is throughout life by means of gills. 



3. The Rabbit. The skin of the rabbit is not separated from 

 the body walls by large lymphatic spaces as in the frog. On the 

 contrary, when we place a rabbit on its back and make a longi- 

 tudinal incision from chin to pelvis, the skin has to be separated 

 from the body walls with the aid of the flattened handle of the 

 scalpel, and even then a thin sheet of (cutaneous) muscle, con- 

 taining numerous minute blood-vessels, will probably adhere to it. 



The abdominal cavity (ccelom) may now be opened out by the 

 removal of its thin muscular walls. Its anterior boundary is a 

 concave moveable partition (the diaphragm) separating it from 

 an anterior thoracic cavity containing the lungs and the heart. 

 This diaphragm behind the lungs is a very characteristic mam- 

 malian structure. The pink lungs may be seen through it. 

 And if we prick it at one side, the lung of that side will be seen 

 at once to collapse. The thoracic cavity may now be opened 

 out, as in Fig. 1 6, by cutting through the ribs with bone forceps, 

 and removing most of the sternum. A ventral bridge support- 

 ing the diaphragm should however be left. 



1. The Alimentary System. Four pairs of salivary glands pour 

 their secretion into the mouth. These are 



a. The Submaxillary, a reddish gland lying between the two 

 divisions (rami) of the lower jaw. The gland of either side 

 meets its fellow in the mid-line. 



b. The Sublingual) small and slightly anterior to the Sub- 

 maxillary. Both these glands send ducts forward which open 

 into the floor of the mouth. 



c. The Parotid, seen by dissecting away the skin in front of 

 and below the base of the external ear. Its duct passes forward 

 into the mouth. 



d. The Infra-orbital, seen by removing the eye-ball. It lies 

 in the anterior and inferior division of the socket, its duct 



