92 MOSTLY MAMMALS 



they may accordingly be regarded as the ancestral type. In 

 the intermediate deposits of Monte Hermoso we meet with 

 other glyptodons, 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 representatives of the 

 group, while others belong to the same genera as those 

 found in the Pampas. 



Passing on to a survey of the leading t3'pes 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 glyptodon was originally applied. 

 The carapace in this form is characterised 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 carapace 

 forms a nearly regular oval dome, with the plates on the 

 front and hind margins knobbed and ridged. Although in 

 the specimen first sent to England the tail of another 

 species was unfortunately affixed 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 from 

 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 

 glyptodons, as they may be conveniently termed, were suffi- 

 ciently large and bizarre to have stood alone in the world, 

 they were exceeded in size and strangeness of form by a still 

 more extraordinary creature. In this stupendous monster, 

 which measured upwards of 1 1 ft. 8 in. in a straight 

 line, the carapace is characterised by its peculiar hump- 



