94 Dr. Burmeister on the Species of Glyptodon 



which receives the ribs. But below the lumbar canal, there are 

 on each side some rather large foramina for the nerves which 

 issue from this part of the myelon. I have counted m the two 

 lumbar canals which are in the Museum, belonging to Glyptodon 

 clavipes, six of these foramina, and in the same canal of the G. 

 spinicaudus seven, which proves that the number of vertebrae 

 united in this canal are six in the first species and seven m the 

 second. There are probably corresponding difierences in the 

 anterior part of the vertebral canal of the two species, that of 

 the G. clavipes being much larger and consequently more 

 numerous in the vertebrae. The last part of the lunibar canal 

 immediately unites with the sacrum without any articulation ; 

 the two appear to be the same bone. 



The OS sacrum is formed of nine vertebrae united in one sohd 

 mass, which is broad and thick at the commencement, thin, long, 

 and high in the centre, and thick with two long prolongations, 

 one on each side, at the end. The first part is composed of 

 three rather short vertebrae, which unite forward with the pelvis, 

 and constitute mth it a very high crest, on which the shell of 

 the animal is supported. The second part is composed of five 

 rather long vertebrae, and is in the figure of a curved tube, with 

 a high crest on its upper part. Five foramina on each side of 

 the tube, for the nerves of the myelon, indicate the number of 

 vertebrae in this part of the sacral bone. At the end, it extends 

 at its base into a solid and thick mass, which assumes the form 

 of the body of a vertebra, and is actually the last vertebra of 

 the sacral bone. On each side of it a horizontal prolongation 

 extends, smooth and broad, which corresponds to the transverse 

 process of the vertebra, and by this prolongation the os sacrum 

 unites for the second time with the pelvis. Another small pro- 

 longation of the penultimate vertebra also unites with this hori- 

 zontal branch. The sacral bone of the Armadillos is formed in 

 the same manner, especially that of the Mataco. 



The pelvis is the largest part of the skeleton, and is of a very 

 peculiar form. Its thickness is caused by the fact that the whole 

 weight of the shell of the animal is superimposed on it, as it ia 

 the only bone which unites immediately with the shell. For 

 this reason the pelvis extends forward and backward into two 

 great perpendicular alae which gradually augment into very broad 

 and strong crests, armed with many obtuse tuberosities, which 

 impinge upon other similar ones on the inferior surface of the 

 shell, having between them large cushions of an elastic cartila- 

 ginous substance, to sustain the weight of the shell more easily, 

 and to permit its more facile elevation during the movement of 

 the body. The anterior prolongations are placed across the spine, 

 and belong to that part of the pelvis known by the name of the 



