1862.] 321 



crest, shows that it was thickest at the sixth and seventh vertebrae (of 

 the thirteen), and that it became thinner both anteriorly and pos- 

 teriorly. 



The spinous process of the twelfth vertebra, forming the termina- 

 tion of the crest, appears to have ended in a free, thin, but rounded 

 edge. What remains of the spinous process of the thirteenth ver- 

 tebra, on the other hand, thins off anteriorly to a natural edge, which 

 is inclined upwards and backwards. Posteriorly the spinous process 

 becomes very thick and stout, and appears to have had a considerable 

 height. It ends in a fractured hinder margin. 



The broad wing-like plates which represent the coalesced trans- 

 verse processes of the first, second, and third vertebrae of the thirteen, 

 exhibit distinct articular surfaces for the capitula and tubercula of 

 ribs. Further back, the natural edges of the apophysial ridges 

 are broken away, up to the eighth vertebra. Here they are entire on 

 the left side and broken on the right ; but, curiously enough, the 

 broken processes are higher than the entire ones, so that the transverse 

 processes in this region of the body must have been asymmetrically 

 developed. The thirteenth vertebra presents peculiarities which 

 could only be made intelligible by a lengthened description, and by 

 figures. The contours of the articular processes become first di- 

 stinctly traceable at the posterior part of the eleventh vertebra. They 

 are better marked at the posterior part of the twelfth, and at the an- 

 terior part of the thirteenth vertebra. 



The nervous foramina are not intervertebral, but pierce the arches 

 of the vertebrae throughout the series. In the thirteenth the outlet 

 of the foramen is separated, by a longitudinal bar of bone, into an 

 upper and a lower division. 



The posterior part of the thirteenth vertebra is much injured, and 

 does not adjust itself naturally to the anterior end of that part of the 

 lumbar region of the vertebral column (consisting of two vertebrae) 

 which remains continuously anchylosed with the sacrum. One or 

 two vertebrae may possibly be wanting, or even three ; but I conceive 

 the last to be the extreme limit of the deficiency*. 



The great Priodont Armadillo has twenty dorso-lumbar vertebrae. 

 If the Glyptodon had the same number, there would be three missing ; 



* Unless I greatly err in ray interpretation of the photographs, these three 

 missing vertebrae are preserved in the Turin Glyptodon. 



2 A 2 



