DESCRIPTION OF THE PLATES. 



PLATE I. 



A side view of the carapace and exposed parts of the internal skeleton of the 

 Gigantic Armadillo {Glyptodon clavipes. See the descriptions of the specimens 

 Nos. 524 to 541 inclusive). 



The parts delineated in outline are wanting in the original specimen : the 

 lower jaw and the tessellated helmet, or dermal bony defensive covering of the 

 skull, are restored on the authority of an original sketch of an entire specimen 

 of this species of Glyptodon transmitted to Sir Woodbine Parish from Buenos 

 Ayres. The bones of the fore-foot are given from the figures illustrating the 

 memoir by Professor D'Alton, published in the Transactions of the Berlin Aca- 

 demy for the year 1836, taf. ii. The restoration of the defective parts of the 

 margin of the carapace is made according to the analogy of the parts pre- 

 served. 



The fossil tail, which was received subsequently to the printing of the de- 

 scriptions of the fossils in the present Volume, measures one foot six inches in 

 length, is almost circular at its base, and becomes slightly depressed towards its 

 apex ; it is gently curved with the concavity upwards through its whole extent, 

 and consists of a series of caudal vertebrae inclosed in an inflexible sheath com- 

 posed of closely united dermal ossicles of various forms and sizes, but disposed 

 in a regular and beautiful pattern. The osseous substance of the sheath in- 

 creases in thickness from half an inch near its base to one inch and three quar- 

 ters near its obtuse apex. The dermal ossicles are united to the internal skeleton 

 of the tail, and defended from outward pressure by processes which radiate from 

 the bodies of the caudal vertebras (see Plate II. fig 4.). The dermal armour 

 consists of central, large, or principal ossicles, and peripheral, small, or accessory 

 pieces, the latter occupying the interspaces of most of the larger ossicles in a 

 single series. The larger ossicles differ in size, increasing as they approach the 





