117 



The component ossicles support on their outer surface a central, large, 

 subpentagonal or subcircular flattened eminence, surrounded generally 

 by five or six smaller discs ; both being rough, but especially the peri- 

 pheral ones. In the ossicles near the margins of the carapace the 

 middle eminence increases, whilst the peripheral tubercles diminish or dis- 

 appear. At the anterior margin the middle eminence extends outwards 

 and forwards as a transversely oblong obtuse projection ; at the lower 

 margins near the posterior part of the carapace it extends outwards in 

 the form of an angular process : the ossicles at the posterior margin are 

 the largest, and have a pentagonal shield-shaped figure ; the two smaller 

 sides being wedged into the interspace of the two ossicles of the penulti- 

 mate row. 



None of the ossicles are modified, as in the smaller Armadillos, to 

 form transverse bands connected together by moveable joints, and 

 allowing the carapace to be closed over the retracted head and legs : 

 such a defensive modification of the bony armour was not required for 

 the gigantic Glyptodon. 



There are forty-four transverse series of ossicles in the present cara- 

 pace which extend from above, downwards and obliquely backwards : 

 the longest series at the middle and broadest part of the carapace con- 

 tain each seventy ossicles ; the number gradually decreasing, as the 

 carapace contracts in width towards the two extremities, the anterior 

 margin being composed of sixteen ossicles, the posterior one of twenty- 

 five ossicles : the total number of these dermal bones maybe estimated 

 at above two thousand in the carapace of the trunk of the Glyptodon 

 clavipes. To these, in the consideration of the dermo-skeleton of the 

 extinct species, must be added the casque defending the head and the 

 verticillate armour of the short and thick tail, both of which are deficient 

 in the preseut specimen. 



From the tertiary deposits of the Pampas of Buenos Ayres. 



Pui-chased. 

 542. An anterior marginal ossicle of the carapace of the Glyptodon clavipes. 



From the tertiary deposits of the Pampas of Buenos Ayres. 



Purchased. 



