MAMMALIA. 



445 



families to hold their own. Serious charges are brought 

 against the rats of being the carriers of various diseases, e. g., 

 of the bubonic plague. (Figs. 236-238.) 



FIG. 237. 



FIG. 237. The Fox Squirrel (Sciurus ludoTicianus). Photographed by Folsom. 



FIG. 238. 



FIG. 238. Porcupine (Erethison). By Dr. J. W. Folsom. 



Questions on the figure. To what order of mammals does the 

 porcupine belong? What are its peculiarities of habit and structure? 



Order 7. Insectivora (insect-feeders}. These are small 

 mammals with clawed digits, which feed on insects and other 



