86 Dr. Burmeister on the Species of Glyptodon 



the adult state of the animal, and for this reason the shells are 

 generally fractured or broken on the edges. Complete shells, 

 with all the parts and tubercles on the edges, are very scarce, 

 and rarer in proportion to the youth of the animal. 



As regards the specific differences between the Glyptodons of 

 this country, I cannot distinguish amongst our rich collection 

 of Buenos Ayres more than three — G. clavipes, Owen, G. tuher- 

 culatus, Owen, and a species which I provisionally name G. spini- 

 caudus, for want of the original works which describe other 



species. • • v i 



The most abundant amongst these three species is the last, of 

 which we have in the Museum an almost entire shell, a complete 

 skeleton, and more or less important remains of three individuals. 

 The species is distinguished easily by its short and conical tail, 

 having seven rings of large conical tubercles ; and for this reason 

 I have given it the name of G. spinicaudus. Probably the G. 

 omatus is identical with this species. As the shape of the tail 

 is the most important feature, we shall begin with its descrip- 

 tion. 



It is 32 inches in length, 14 in width at the base, and 

 4 at the apex, which is obtuse and round. At the base are 

 seen six rings of conical tubercles, which are more or less narrow. 

 Each ring is composed of three bands of plates, the last one 

 being formed of the great tubercles, whilst the two preceding 

 ones are smooth, and almost wholly covered by the anterior 

 rings. The first ring is the largest, and of a transversely ellip- 

 tical shape, having twenty-three tubercles on the posterior edge, 

 the nine lower ones being smooth, and the upper ones more 

 elevated into a conical point according as they approach the 

 middle of the dorsal surface. The second ring is of an almost 

 circular figure, and with eighteen tubercles on the edge, the 

 inferior surface being smooth in almost all the lower rings. In 

 the same manner, the third ring has fifteen, the fourth eleven, 

 the fifth nine, the sixth seven tubercles ; and the extreme por- 

 tion is formed by a ring of five, including amongst them three 

 at the apex itself. Of all these tubercles, those of the middle of 

 the dorsal surface are always the largest, and prolonged into a 

 conical point. The shell of this species is in its general form 

 more spherical than that of some of the others. Its length, follow- 

 ing the curve, is about 3^ yards {varas), and its width about 2^ ; 

 only the posterior part near the tail is a little uncovered ; the 

 longitudinal diameter is 5^ feet, and the transverse diameter is 

 about 3^. The surface of the plates is very rough, much more so 

 than in the other species, and the size of each plate smaller. The 

 central hexagon of the dorsal plates of the shell is smaller than in 

 G. clavipes, and for this reason the difference between the central 



