EDENTATA. 



offers a very remarkable structure. The ungueal 

 phalanges, like tliost 1 of tlie Sloth, are restricted 

 in their motion to simple Hexion, in which 

 position they are retained during repose by 

 strong ligaments. In the Myrmecopnaga the 

 terminal phalanges are deeply grooved in the 

 margin ; in the latter they are bifid. The pha- 

 langes of the fingers themselves are very une- 

 qual in length and thickness. The middle 

 ringer is of extraordinary size, every articula- 

 tion being very robust, and almost twice as 

 thick as either of the others; the next on each 

 side are nearly as long but much smaller, and 

 the outer shorter still and very slender. The 

 outer finger has no claw ; the four others are 

 furnished with claws. The hand in Dani/pus 

 and l)n/c/en>ims is also of a very remarkable 

 conformation, particularly in the gigantic spe- 

 cies of Armadillo, 1'riinlonta gigantea (jig 37) 



Fig 37. 



Hand of the Gigantic Armadillo. 



of Fr. Cuvier. Amongst the peculiarities of 

 structure in this animal are the following. 

 In add.tion to several remarkable anomalies 

 in the carpal bones, the bone which results 

 from tle ossification of the Jleior profundus 

 muscle is very large, developed posteriorly 

 into a large and irregularly formed head, 

 articulated by large surfaces to the os semi- 

 lunure and pisiforme, presenting concave sur- 

 faces on the side of the fore-arm, and termi- 

 nating towards tlie hand by an enlargement 

 which is compressed and smaller than the head. 

 The metacarpals are no less extraordinary. 

 Those of the thumb and index, as well as their 

 phalanges, are slender, of the usual construc- 

 tion, but that of the middle finger is irregularly 

 rectangular and broader than it is long; and the 

 phalanx which it supports is of a corresponding 

 form and size, being extraordinarily short and 

 broad. The corresponding bones of the fourth 

 finger are similarly formed, but somewhat 

 smaller. The ungueal or terminal phalanx of 

 the middle finger is enormously large and 

 strong, curved outwards, and having at its base 

 a large bony hood or case for the lodgement of 

 the claw ; the terminal phalanx of the fourth 

 finger is similar, but of somewhat smaller di- 

 mensions. The fifth or little finger is much 

 smaller, but is furnished with a claw of some 

 size. The conformation of the hand of this 

 animal affords a most formidable weapon, or 

 as a powerful fossorial instrument, in the three 

 outer claws, whilst the two inner ones are only 

 formed for scratching or other similarly slight 

 actions. 



The posterior extremity of the Edentata 

 imi/icr oilers jierlinps less striking peculiarities 

 ol structure. \The femur in general is of mo- 



derate length, but large and strong; and an 

 elevated crest, arising from the great trochanter, 

 extends nearly the whole length of the bone. 

 In the Ant-eaters and the Megatherium, it is 

 particularly broad and flattened, and the greater 

 and lesser trochanters are not particularly pro- 

 minent. In the genus Dusypus the great tro- 

 chanter on the contrary is of great size, and 

 from the middle of its outer margin arises a 

 large process which is directed outwards. The 

 tibia mAJibula m the latter genus are extremely 

 broad, arched, and anchylosed at both extremi- 

 ties. In the Ant-eaters, on the other hand, these 

 bones are of the ordinary form, and have no 

 osseous union. In the Megatherium they are 

 united by the superior third of their length, and 

 closely in contact at the lower part ; they are 

 both short and extremely thick, particularly the 

 tibia. The tarsus is composed in the two-toed 

 Ant-eaters of at least eight distinct bones, the 

 largest of which is a supernumerary 

 bone, situated at the inner part of the 

 foot, upon the scaphoid; it extends back- 

 wards as far as the tuberosity of the 

 os calcis, and thus forms a broad base 

 to the posterior part of the sole of the 

 foot. The Myrmecopliaga jubata has 

 also a supernumerary bone, but of 

 smaller dimensions; but the Armadillos 

 and Orycteropus have but the seven or- 

 dinary bones of the tarsus. The metatarsal 

 bones and the toes are probably invariably five 

 throughout the Edentata proper; the toes of 

 the posterior extremity offer few peculiarities of 

 any consequence. Both the anterior and poste- 

 rior feet of the Megatherium are peculiar in their 

 structure. In the former, those fingers which 

 are completely formed are the three middle 

 ones, the little finger being rudimentary, and 

 the thumb having no claw. The ungueal pha- 

 langes of the three former are enormously deve- 

 loped, principally as regards the bony enve- 

 lope for the base of the claw ; the size and 

 thickness of which indicate that the claws 

 themselves must have been of great size and 

 immense strength, and have afforded powerful 

 implements for tearing up the suiface of the 

 ground in search of roots. On the hinder 

 foot, there is a single toe of a similar con- 

 struction, which is the third ; the fourth and 

 fifth, although of considerable size, bore no 

 claws. This enormous extinct animal is cer- 

 tainly among the most extraordinary produc- 

 tions of the ancient world. Of dimensions the 

 most unwieldy, and with a skeleton as solid as 

 that of the most enormous amongst the Pachy- 

 dermata, we find a cranium, and especially 

 teeth, which exhibit a very near relation to those 

 of the Sloth, and members which are no less 

 remarkably allied to the Ant-eaters and the Ar- 

 madillos. However the difference in bulk may 

 appear at first sight to interfere with the idea of 

 these affinities, and however difficult it may be 

 at once to reconcile the relation between a 

 small active animal like the Armadillo, or 

 an inhabitant of trees like the Sloth, and 

 this enormous and unwieldy tenant of the 

 earth's earlier surface, the affinities are neither 

 less true nor more probable than those which 

 subsist between the light rabbit-like hyrax 



