THE GRAY SQUIRREL 403 



it from the roof of the mouth, or hard palate, separates the 

 mouth from the pharynx (Fig. 213, 6). Imbedded in the soft 

 tissues of the soft palate are the tonsils, two small oval bodies 

 the function of which is unknown. The nostrils open pos- 

 teriorly (Fig. 213, 3) into the pharynx. The Eustachian tubes 

 from the ears enter the pharynx at the sides. 



A short, straight oesophagus (Fig. 213, 7, 8) leads to the 

 sac-like stomach (Fig. 213, 9), passing through a muscular 

 partition called the diaphragm (Fig. 213, 19), which separates 

 the heart and lungs in the thoracic cavity from the organs 

 of the abdominal cavity. In the first 

 fold of the intestine is the pancreas 

 (Fig. 213, 13), an extended mass of 

 spongy tissue roughly suggesting a 

 bunch of grapes. The liver (Fig. 

 213, 11) is large and is divided into 

 several lobes. The intestine is very 

 long and much coiled. A clearly 

 marked anterior portion, the small 

 intestine (Fig. 213, 10), can be distin- 

 guished from the posterior portion, or FlG - 214 - Caecum and Ver- 

 rectum (Fig. 213, 14). At the junction miform A PP eildix of the 



. , , n . , /. . Squirrel 



of the small intestine and rectum is 



the cwcum (Fig. 214), from which projects a closed finger-like 

 appendix vermiformis. 



Ductless Glands. Several glands, called ductless glands 

 (owing to the absence of a duct leading from them), are 

 present in vertebrates. With the single exception of the 

 spleen (mentioned in each case in the course of the statements 

 concerning the digestive system) they have not been referred 

 to in our brief discussion of the internal anatomy of the 

 classes of vertebrates, but as they show plainly in the squirrel, 

 attention may be called to them at this time. They are, 

 besides the spleen (Fig. 213, 15), the adrenal capsules (Fig. 213, 16), 



