388 



forms an angular projection ; the ordinary number of peripheral tubercles 



being seven. 

 Fig. 5. The external surface of a marginal ossicle from the lower border of 



the carapace in which the peripheral tubercles are obliterated, and the 



median eminence is developed into a thick pointed process. 

 Fig. 6. The external surface of a small portion of the bony carapace of the 



Glyptodon ornatus, showing two complete ossicles. (See No. 554.) 



PLATE V. 



Portions of the bony armour of different Glyptodons or extinct Gigantic Ar- 

 madillos : natural size. 



Fig. 1. The outer surface of a portion of the carapace of the Glyptodon re- 

 ticulars, in the component ossicles of which the central eminence is an- 

 gular in contour and of equal size with the marginal ones, which rarely 

 exceed six in number ; the whole exterior of the carapace, except, pro- 

 bably, at and near its margins, being impressed by channels in the form 

 of a net-work. (See Nos. 556 and 557.) 



Fig. 2. A view of the fractured margin of two anchylosed ossicles of the 

 same carapace, showing its thickness. 



Fig. 3. A portion of the carapace, including six component ossicles, of the 

 Glyptodon tuberculatus. They are square-shaped, and their outer surface 

 is divided into more numerous elevations, separated by narrower channels, 

 which intersect or unite with each other to form a closer network than 

 in Glyptodon reticulatus : d is the uniting suture of the ossicles. 



Fig. 4. The internal surface of the same portion of the carapace of the 

 Glyptodon tuberculatus. 



Fig. 5. The sutural margin of three dermal ossicles of the Glyptodon tubercu- 

 latus, showing the thickness of the carapace. 



PLATE VI. 



The molar teeth of the lower jaw of the extinct gigantic marsupial Pachyderm 

 of Australia {Diprotodoji australis) : natural size. 



Fig. 1, An ideal outline of the first molar tooth, giving its size, as indicated 



