Mr. Owen on the Glyptodon clavipes. 99 



form of beams. If a covering consist of flexible material, then the surface of sup- 

 port must be to a certain extent continuous or extended ; and it would seem that it 

 is on this principle that the iliac bones of the Elephant are arched outwards so as 

 to afford an extended surface of support to its yielding, though dense, integument : 

 we may therefore presume that a like relation subsisted between the expanded ilia 

 of the Megatherium and its integument. The compact covering of the Armadillo 

 rests upon a more contracted basis ; and when we compare the mechanism of this 

 support with the scaffolding of an inflexible roof, the same principle may be traced 

 in both the natural and artificial architecture. It is by this chain of reasoning 

 that I have been led to a conclusion, in respect of the relations of the iliac bones 

 of the Megatherium to its integument, different from that which has been cited. 

 But the part of the pelvic structure of the Megatherium, which, perhaps, tells the 

 strongest against its possessing a ponderous coat of mail, is the paucity of the sacral 

 vertebrse, conjoined with their structure. These, instead of being ten or twelve, do 

 not exceed four in number, and they are further characterized by the comparatively 

 small size of their spinous processes, which are not locked together as in the 

 Armadillos, but are separated by intervals as in the Sloths. 



It will he remembered that the estimable and justly celebrated author, from 

 whose reasonings on the osteological relations of the Megatherium I have thus far 

 ventured to dissent, enunciates his conclusion with philosophic caution, and states 

 it to be probable that the Megatherium possessed a bony coat of mail. 



But that which Cuvier and M. Laurillard have ventured to regard as only pos- 

 sible, and Dr. Buckland as probable, M. de Blainville has since announced to 

 be a positive fact. He has communicated to the Academy of Sciences the 

 statement that bones of the Megatherium have recently been discovered, accom- 

 panied with fragments of a carapace belonging indubitably to the same animal* ; 

 and he adds, that the association of a bony armour with the internal skeleton of 

 the Megatherium can be demonstrated as surely by a priori reasoning as by the a 

 posteriori fact. 



Some interesting and novel arguments, deduced from the osteological structure 

 of the Megatherium, might have been expected from so accomplished a Compara- 

 tive Anatomist as the successor to Cuvier; but M. de Blainville restricts himself 

 to the mere repetition of the conditions of the skeleton already argued upon by 

 Dr. Buckland as indicating a probability that the sustaining of a heavy coat of 

 mail was thereby provided for, affirming that the Megatherium is proved to be cer- 



* " De nouvelles decouverts d'ossemens de Megatherium accompagne de fragmens de carapace, pro- 

 venant indubitablement du meme animal, outre celles d'ossemens d'autres especes de Tatous," etc. — 

 Comptes Rendus, 21 re Janv. 1839, p. 51. 



o2 



