,. r, . 



Photo: British Museum (Natural History). 



"FORTRESS" OF THE MOLE (in cross section) 



The large mounds of earth noticeable where moles are abundant are the "fortresses," while the smaller mounds are made 

 by the earth thrown up during the construction of the "runs." The sexes build separate fortresses, and that of the female 

 an example of which is shown here in section is the larger, being used as a nest for the young. 



Photo: IT. .V. Berridge. 



TWO-TOED SLOTH OR UNAU 



This old-fashioned type (Cholcepus didactylus) lives in the forests of South America, e.g. in 

 Nicaragua. It is highly specialised for arboreal life, moving slowly about back-downwards 

 along the under side of the branches, holding on with the recurved claws on the two fingers 

 and three toes. On the ground it moves awkwardly. It feeds on leaves, and has a stomach 

 with several chambers. The hair is coarse and shaggy and affords a basis for the growth of 

 aunicellular green alga. The teeth are simple pegs without enamel, and seem to be confined 

 to one set. The two-toed Sloth has usually six neck vertebrae and the three-toed Sloth has 

 usually nine, thus illustrating divergence from the normal mammalian number seven. 



