324 BRANCH CHORDATA 



are chiefly tropical. The name, Edentata, is somewhat mislead- 

 ing, as teeth are not wholly lacking, except in the family Myrme- 

 cophag'idce and the African genus Manis, which, having no use 

 for teeth, have lost them. Front teeth are always lacking in this 

 order. None of the teeth in the adult have enamel. They are 

 said to be stupid and sluggish creatures, and, except in the ant- 

 eaters, the brain is devoid of convolutions. 



Ant-eaters (Myrmecophag'idce). — This family consists of three South 

 American genera, all without teeth and with long protrusible, ^-iscid tongues, 

 the sahvary glands being highly develojjed. The snout is long and the body 

 covered with long hair, while the tail is long and bushy. The claws are 

 long and powerful, enabhng them to tear open the an( -hills, or, in the ar- 

 boreal forms {Tamaii'itiia and CycloLu'rus), to tear the bark from trees and 

 search for insects or to defend themselves. 



The great ant-eater (Myriiiccophagiilfr jubata) is said not to "fear the 

 presence of the serpent's fold or the teeth of the jaguar," and will rip 

 open a big dog with its claws before the dog's teeth can make an impression 

 through the shaggy hair. Including the tail, this species may reach a 

 length of 6 or 7 feet. The tail is 2 feet long and said to be the largest of 

 that of any mammal. The great ant-eater sleeps through the day in a kind 

 of " lair" in the tall grass, where it lies " on one side with its head buried 

 in the long fur of the chest, the legs folded together, and the huge tail 

 curled around the exposed side of the body."' They are numerous in 

 their region, although the mother produces but one each year. The young 

 stays with the mother a year, riding on her back when little. 



The sloths (Bradypod' idw) , of South America, are arboreal forms, with 

 very long anterior limbs, short tails, and round heads. Instead of the usual 

 seven cervical vertebrae, the three-toed sloth {Brad'y/iiis) or " Ai," so called 

 from its plaintive cry, has the unusual number of nine, while the two-toed 

 genus {Cholae'pus) has the exceptional number of six. The toes have long, 

 recurved, non-retractile claws for clinging to the branches of trees. The feet 

 are like hooks with the fingers bent under them, hence the>' walk slowly 

 and clumsily on the ground, but climb about \Aith ease in the trees, where 

 they live continually day and night, Iianging back do'\\'nward, even in sleep, 

 from the lower side of the limb. They ne\'er descend to the ground unless 

 compelled to do so, but spring from tree to tree in search of food, which con- 

 sists of leaves and green shoots. They are nocturnal. Their hair is long 

 and shaggy and covered with minute green alga?, giving the animal an al- 

 most perfect resemblance to a lichen-eo^■ered branch. This may be taken 

 as an example of commensalism between animals and plants. 



Armadillos (Dasypnd'idcr). — There are se\-eral genera of armadillos (Fig. 

 26.5), and they are fovmd chiefly in South America. They are also known 

 in Central America, and one species is said to occur in Texas. They are the 

 only mammals in which the dermis develops into hard bony plates like those 

 of the turtle, while the hair on the dorsal part of the body is replaced by 

 horny scales covering the bony plate. 



" Traces of dermal armature (-xist in one or two genera of the whales."^ 



' Inger.soU, p. 471. 

 - Beddai-d, p. 173. 



