92 



DR RICHAED J. A. BERRY. 



marked in the caecum than in other parts of the intestinal 

 canal. 



EODENTIA. 



Of this order the rabbit, with a caecum and a moderately 

 long appendix, constitutes the type. The other rodents examined 

 are as follows : — 



Mus musculus, the house mouse. 



Mus decumanus, the rat. 



Castor fiber, the European beaver. 



Dolichoius ijataclionica, the Patagonian cavy. 



Sciurus vulgaris, the common squirrel. 



Dipus jacidus, the Egyptian jerboa. 



Dasyproda cristata, the West Indian agouti. 



In the mouse and the rat the Ccecum is slightly constricted 

 about its middle. This is figured diagrammatically in figure 4. 



Basal Portion of 

 Caecum 



■Site of the 

 Lymphoid Tissue 



'.'/lA 



Apical Portion of 

 Caecum 



Fig. 4. — Diagrammatic scheme of the ciecum of a mouse. 



This constriction, as shown in the figure, subdivides the ciecum 

 into two parts, an apical portion and a basal portion. The basal 

 portion in both contains little or no lymphoid tissue. The apical 



