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 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 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 dzzarre 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 11 ft. 8 in. in a straight 
line, the carapace is characterised by its peculiar hump- 
