GIGANTIC EXTINCT ARMADILLOS. 145 



conclusions ; not only do the vertebral centra become more rudimentary 

 as the young condition is departed from in the life-history of the indi- 

 vidual tortoise, but the centra also become successively more rudimentary 

 as we pass from the less completely armored genera Sp>hargis and Tri- 

 onyx, to the more completely armored Testudo and Cistudo. 



Like the tortoises, our huge animal had an arrangement of the neck 

 vertebras whereby he could withdraw his head slightly backward in case 

 of an attack, so as to bring his head-shield to fit closely against his cara- 

 pace. The atlas or first joint of the neck was separate, the next four 

 were united, the sixth was separate, and a " trivertebral bone," which 

 seems to have taken a share in the neck as well as in the thorax, fol- 

 lowed next, and probably was the bone which enabled the creature to 

 retract its head somewhat ; next followed ten united rib-bearing trunk- 

 vertebras, which Prof. Burmeister has aptly called the " dorsal tube " {see 

 cross-section, Fig. A). Succeeding the "dorsal tube" are eight lum- 

 bar and probably eight sacral vertebras firmly united together and to 

 the ilia ; following these, come twenty-one caudal or tail bones, footing 

 up a total of fifty-six segments in the entire spinal column, which is not 

 far from the number found in living species, though only about one- 

 fourth as many are united together in them as in our fossils. The plates 

 of the carapace were united by suture in the fossil species, rendering the 

 armor as rigid as the carapaces of land-tortoises. In living forms, the 

 plates, in some species at least, are slightly separated by intervening 

 integument, rendering the armor more or less flexible throughout. 



The remains of the LToplophoridce better known by Prof. Owen's 

 older name as the Glyptodons have been found mostly in the bone-caves 

 of Brazil, and in the alluvium and pampean Pliocene of Eastern and 

 temperate South America. The finest collection of their remains in ex- 

 istence is in the Public Museum of Buenos Ayres. They were probably 

 contemporaneous with some of the great Carnivora, whose remains have 

 also been found in the caves. One of these, the sabre-toothed tiger 

 (3fachairodus), would, no doubt, have frequently rendered the almost in- 

 vulnerable armor of the giant (but perhaps harmless) armadillo of great 

 service, within which he could feel himself secure from the attacks of 

 such a well-armed foe. 



The restoration is one-eighteenth of the natural size, and is based on 

 the figures in Burmeister's work. It is believed to be approximately 

 correct, since nothing was needed to make the originals assume the ap- 

 pearance of life except to clothe the skull and neck w r ith flesh, and fur- 

 nish the extremities with claws and hoofs, muscles and tendons. The 

 animal was between nine and ten feet in total length, and stood about 

 four and a half feet high at the highest part of the back. Prof. Bur- 

 meister has christened the species Panochthus tuberculatus. 



VOL. XIII. 10 



