448 ZOOLOGY SECT. 



is divided into two parts, an upper or nasal division and a lower 

 or buccal division, by the soft palate. The passage of the posterior 

 nares is continuous with the nasal division, at the sides of which 

 are the openings of the Eustachian tubes. The nasal division is 

 continuous with the buccal division round the posterior free edge 

 of the soft palate. From the buccal division leads ventrally the 

 slit-like opening of the glottis l into the larynx and trachea ; over- 

 hanging the glottis is a leaf -like movable flap (Fig. 1099, ep). 

 formed of a plate of yellow elastic cartilage covered with mucous 

 membrane ; this is the epiglottis. Behind, the pharynx becomes 

 continuous with the ossophagus or gullet (ces.). The latter is a 

 narrow but dilatable muscular tube which runs backwards from 

 the pharynx through the neck and thorax to enter the cavity of the 

 abdomen through an aperture in the diaphragm, and opens into the 

 stomach. 



The stomach (Fig. 1100) is a wide sac, much wider at the cardiac 

 end, at which the oesophagus enters, than at the opposite or pyloric 

 end, where it passes into the small intestine. The small intestine 

 is an elongated, narrow, greatly coiled tube, the first part of which, 

 or duodenum (du and du'), forms a U-shaped loop. The large 

 intestine is a wide tube, the first and greater part of which, termed 

 the colon, has its walls sacculated, and is continued into a narrow, 

 smooth- walled posterior part or rectum (ret.). At the junction of 

 the small with the large intestine is a very wide blind tube, the 

 ccecum, which is of considerable length and is marked by a spiral 

 constriction, indicating the presence in its interior of a narrow spiral 

 valve. At its extremity is a small, fleshy, finger-like vermiform 

 appendix. 



The intestine, like that of the Pigeon, is attached throughout 

 its length to the dorsal wall of the abdominal cavity by a mesentery, 

 or fold of the lining membrane or peritoneum. 



The liver is attached to the diaphragm by a fold of the peri- 

 toneum. Its substance is partly divided by a series of fissures 

 into five lobes. A thin-walled gall-bladder lies in a depression on 

 its posterior surface. The common bile-duct (c.b.d.), formed by the 

 union of the cystic duct from the gall-bladder and hepatic ducts from 

 the various parts of the liver, runs to open into the duodenum near 

 the pylorus. 



The pancreas (pn.) is a diffused gland in the fold of mesentery 

 passing across the loop of the duodenum. Its single duct, the 

 pancreatic duct (pn. d.), opens into the distal limb of the loop. 



Circulatory Organs. The heart (Fig. 1101) is situated in 

 the cavity of the thorax, a little to the left of the middle line, and 

 lies between the two pleural sacs enclosing the lungs. Between the 



1 The term glottis is more strictly applied not to this slit, but to the slit- 

 like aperture between two folds of the mucous membrane within the larynx 

 the vocal cords which constitute the chief parts of the vocal apparatus. 



