52 



KNOWLEDGE. 



[Makch 1, 1894. 



modifications are needed in the internal skeleton. Here 

 we find, for instance, as shown in the foregoing figure, 

 that nearl.y the whole of the vertebrse are welded together, 

 sD that a large portion of the back-bone forms a continuous 

 solid tube. The vertebrae of the neck are also very short, 

 and may be partially united, so that the movements of the 

 head must have been somewhat limited. The reader will 

 not fail to notice also the great strength and upright 

 position of the haunch-bones, and the powerful build of 

 the legs and feet ; the latter terminating in five toes, 

 armed with broad flattened nails. As an illustration of 

 the various modifications of the same general plan of 

 structure in use in the animal kingdom, it may be well to 

 point out how essentially the arrangement of the armour 

 of a glyptodont differs from that of an ordinary tortoise or 

 turtle. In the latter the carapace is completely welded to 

 the ribs, which are situated externally to the haunch and 

 shoulder bones ; whereas in a glyptodont there is no sort of 

 connection between the carapace and the ribs, while the 

 latter are internal to the haunch and shoulder bones. In 

 these respects the leathery turtle holds a somewhat inter- 

 mediate position between ordinary turtles and the glypto- 

 donts, the carapace being composed of polygonal plates 

 totally unconnected with the ribs, while the latter are 

 situated externally to the bones of the shoulder and 

 haunch. 



Not less remarkable are the modifications of the 

 vertebrie of the tail for the support of the rings or tube 

 with which the latter is encased. In the first place, most 

 of the vertebras of this region are welded together so as to 

 form a hollow tapering rod ; while from each segment are 

 given off radiating processes upon which the bony plates 

 are borne, and as the whole of the latter are firmly welded 

 together, the entire structure is of great strength. 



When standing with the edges of its impenetrable 

 carapace resting on the ground, its mail-crowned head 

 partially withdrawn within the front aperture of its shell, 

 and only the lower portions of the limbs exposed, a glypto- 

 dont must have been safe from all foes save savage man, 

 and even he must have had a tough job to slaughter the 

 monster, if indeed he ever succeeded in doing so. That 

 man did exist with the later glyptodonts, or those which 

 flourished during the deposition of the Pampean mud, is, 

 however, proved by more than one kind of evidence. For 

 instance, crude drawings of these animals have been found 

 incised on some of the rock-surfaces of Patagonia, while 

 in other cases human implements have been disinterred 

 side by side with the bones and shells. Probably the 

 empty carapaces of the larger members of the group were 

 employed by the primitive inhabitants of Argentina as 

 huts, and it is said that they are sometimes even so used 

 at the present day by the Indians. That these animals 

 were not killed off by any li\ing foe — either human or 

 otherwise — may be taken for granted ; and we must 

 therefore conclude that this result was probably due to 

 the unknown causes alluded to in the first of this series 

 of articles as having brought about the extermination of 

 the larger Argentine mammals. It may be well to men- 

 tion that although some of the living armadillos are 

 carnivorous, it is perfectly evident from the structure of 

 their teeth that all the glyptodonts subsisted exclusively on 

 a vegetable diet. 



The earliest known representatives of the group occur in 

 the older Tertiary beds of Patagonia, and may be designated 

 pigmy glyptodonts, although they have received the 

 uncouth name of Propalchoplojihanis. These creatures, 

 which lived side by side with armadillos nearly akin to 

 existing forms, were the dwarfs of their race, the carapace 

 not being more than a couple of ftet in length. The plates 



of the carapace were smooth and ornamented with a 

 rosette -like sculpture, of which the central ring in the fore 

 part of the shell was raised into a prominent boss. In the 

 form of these plates, as well as in the circumstance that 

 the tail was surrounded from base to tip with a series of 

 knobbed rings, these pigmy glyptodonts resembled the 

 ring-tailed glyptodonts of the pampas, of which they 

 may accordingly be regarded as the ancestral type. 

 In the intermediate deposits of Monte Hermoso we meet 

 with other glyptodonts which, while much larger than 

 those of the Patagonian beds, were generally inferior in 

 this respect to the giants of the Pampean ; some of the 

 species being nearly allied to the small Patagonian repre- 

 sentatives of the group, while others belong to the same 

 genera as those found in the pampas. 



Passing on to a survey of the leading types of these 

 creatures found in the alluvial mud of the pampas, where 

 they occur in great numbers, we may first notice the one 

 to which the name of glyptodont was originally applied. 

 The carapace in this form is characterized by the polygonal 

 plates being nearly smooth and marked by a rosette of 

 incised lines, while those along the margin are raised into a 

 series of bold knobs. In general contour the whole cara- 

 pace forms a nearly regular oval dome, while the plates on 

 the back of the head were knobbed and ridged. Although 

 in the specimen first sent to England the tail of another 

 species was unfortunately afiixed to the carapace, it is now 

 known that the armour of the tail took the form of a 

 number of rings, gradually diminishing in diameter fi-om 

 the root to the tip, and severally ornamented with a series 

 of conical knobs, thus forming a protective case against 

 which little short of a steam hammer would have been of 

 any avail. 



Although one might have thought that these ring-tailed 

 glyptodonts, as they may be conveniently termed, were 

 sufficiently large and hiunrc to have stood alone in the 

 world, they were exceeded both in size and strangeness of 

 form by the extraordinary creature of which the external 

 skeleton is represented in the accompanying plate. In this 

 stupendous monster, which measured upwards of eleven 

 feet eight inches in a straight line, the carapace is 

 characterized by its peculiar hump-backed form, while its 

 margins lack the prominent knobs characterizing those of 

 the preceding group. On closer examination it will be 

 found that each of the component plates of the carapace, 

 instead of being polygonal and marked by a rosette of 

 lines, is rhomboidal and pierced by from two to five large 

 circular holes. From the analogy of the living hairy 

 armadillo — known in Argentina by the name of peludo, or 

 hairy animal — it is quite evident that during life the holes 

 in the plates of the carapace of the extinct monster, 

 which, by the way, may be known as the " club-tailed 

 glyptodont," or technically as Ikniiciirus, must have 

 formed the exits of large bristles, which were equal in 

 diameter to a cock's quill, and were doubtless many inches 

 in length. The whole body of the animal must, therefore, 

 have resembled a gigantic porcupine. Still more extra- 

 ordinary is the conformation of the huge tail, which had a 

 length of about five feet. At its base this appendage 

 was encircled by about half a dozen double bony rings, 

 nearly as large at the base as the iron hoops in the middle 

 of an ordinary beer-barrel ; their component plates being 

 pierced by the aforesaid holes for bristles. The whole of 

 the terminal half of the tail is formed by one continuous 

 piece of hollow bone, which, if we exclude whales, is one 

 of the most massive bony structures in the animal kingdom, 

 and is almost as much as a man can lift. Starting at its 

 base in the form of a nearly cylindrical tube, this sheath 

 rapidly expands at the sides and becomes flattened on 



