BRANCH CHORD AT A: CLASS MAMMALIA 375 



toneal cavity. Within the loop of the pylorus will be 

 found an irregular pinkish mass of tissue, the pancreas. 

 Beneath the stomach on the left side of the body lies a 

 very dark glandular mass not much unlike the liver but 

 altogether detached from it. This structure is the spleen, 

 a ductless gland. 



Note dorsally of the trachea a long tube passing through 

 the diaphragm and connecting the mouth with the 

 stomach. What is this tube ? Note the Eustachian tubes 

 extending from the mouth to the ears. The median part 

 of the roof of the mouth is the palate, hard in front, soft 

 behind. A pair of small bodies at the sides of the soft 

 palate near its hinder end are the tonsils. At the pos- 

 terior angle of the lower jaw are glandular bodies, the sub- 

 maxillary glands, which lead by a short duct anteriorly 

 to open on the floor of the mouth. On the sides of the 

 neck just below the ears are pink or yellowish bodies, the 

 parotid glands, opening anteriorly in the sides of the 

 mouth-cavity. These two sets of glands are collectively 

 known as the salivary glands, the function of which is to 

 secrete the saliva. Push apart the sub-maxillary glands 

 and note below them overlying the trachea on either side 

 two dark-red lobes connected by a band of tissue. These 

 constitute the thyroid gland, another of the so-called 

 ductless glands. Within the thoracic cavity anterior to 

 the heart note a mass of pinkish tissue, the thymus gland. 

 Observe the large masseter muscles, which cover the jaws. 

 What is their function ? On either side of the neck lies a 

 large blood-vessel, the external jugular vein, which col- 

 lects blood from the head and carries it down to the heart. 

 Note the large pectoral muscles which cover the breast and 

 extend out into the arms, and which are so strong and 

 highly developed in the sparrow. The head is supported 

 by large muscles which run down the back of the neck 

 to the ribs. Others are attached to the ribs, which they 



