M. Serres on Glyptodon ornatus. 441 



mentioned that a fragment of the dorsal column had been found 

 adherent to its inner surface, but not in its proper place (see 

 ante, p. 45). This fragment commences at the articulation of 

 the third dorsal vertebra, and includes twelve vertebrae soldered 

 together; except the number of vertebras thus united, it presents 

 nothing in its general configuration that has not already been 

 described by Huxley, and especially by Burmeister in Glyptodon 

 clavipes. 



The number of vertebrae is easily counted by the number 

 of apertures seen in the bottom of the two vertebral channels. 

 These apertures gave passage to the posterior branches of the 

 spinal nerves, and also to venous canals. The median crest in 

 front is cut off very obliquely, thin and trenchant ; it was no- 

 where articulated or even in direct contact with the carapace. 

 Each lamina of the twelfth vertebra of the bone is produced in 

 front into the bottom of each vertebral channel above the la- 

 mina of the eleventh, by an apophysis (at least ?) three centime- 

 tres in length. On each side, this apophysis is held in a sort of 

 mortice, formed by two vertical surfaces, depending from the 

 arch of the eleventh vertebra. There is synostosis; but this 

 must no doubt be ascribed to age. 



The laminae of the twelfth vertebra present analogous mor- 

 tices behind; these, no doubt, received the apophyses of the 

 following vertebra in the same manner. 



Between this point and the vertebrae soldered together to form 

 the sacrum, there exists a gap, which is the more to be regretted, 

 because, the hinder part of the skeleton having, in this indivi- 

 dual, remained in its normal relations to the carapace, the inte- 

 grity of the vertebral column would have enabled us to appreci- 

 ate the true relations of the neck and head with the margin of 

 the cephalic emargination. 



In seeking for the bones of the neck, I met with one which, 

 although not belonging to the same individual, appeared never- 

 theless to be referable to the same species. The articular sur- 

 faces seemed constructed to coincide ; the posterior part of the 

 voluminous apophysis, which surmounts the vertebral gingly- 

 mus, was hollowed by a narrow furrow exactly in relation to the 

 anterior oblique and trenchant extremity of the median crest of 

 Glyptodon ornatus. 



But the skeletal constitution of the neck was not the same 

 here as in Glyptodon clavipes. In place of the trivertebral and 

 pentavertebral bones, named by Huxley and myself, I found 

 two bones, each consisting of four vertebrae. The articulation 

 separating them, the mechanism of which I have already had 

 the opportunity of describing in G. clavipes, instead of existing 

 between the tilth and sixth cervical vertebrae, occurs between the 



