112 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.51. 



As usual in the glyptodonte, the seventh cervical is united solidly 

 with the first and second dorsals. The width of the mass (pi. 3, 

 fig. 7) near the rear is 150 mm. That of G. asper^ appears to have 

 been about 180 mm. wide behind and wider still in front. This 

 mass, as figured and described by Burmeister, had along each border 

 two rather deep notches and three processes. These are not seen in 

 the specimen before us. On each side is an irregular surface, with 

 several small facets for union with the head of the first rib. The 

 motion here was evidently unimportant. The surface on each side 

 for the second rib indicates more liberal movement. On each side 

 below are two large openings for nerves. These divide each into two 

 canals, one opening out on the upper surface of the mass, the other 

 on the lower. The superior openings are much larger than those of 

 Burmeister's figures. At the rear of the mass the postzygapophysial 

 surfaces of the two sides coalesce under the spine. On each lateral 

 process is a surface for union with corresponding surface on the 

 front of the third dorsal. 



The third dorsal and the succeeding ones, up to and including the 

 twelfth are, in the glyptodonts, consolidated into a single mass in 

 which the individual vertebrae can be distinguished only by the 

 foramina for nerves and the facets for the ribs. In G. jyetallferus 

 the floor of the spinal canal is in places less than a millimeter in 

 thickness : in the last dorsal, however, 5 mm. thick. The dorsal spines 

 are greatly reduced and coalesced into a median ridge of small and 

 irregular height. In the series, as preserved, on the assumption that 

 there were twelve, there is missing most of the sixth and of the 

 seventh dorsals and a part of the eleventh. The front of the third 

 dorsal presents, superiorly (pi. 3, fig. 8) a crescentic zygapophysial 

 surface for the second dorsal; also on each side a semicylindrical 

 surface on the lateral process, for union with a corresponding surface 

 on the second dorsal, already noted above. Above the rear of the 

 articulatory surfaces for the fourth pair of ribs the bone correspond- 

 ing to the fourth vertebra is 109 mm. wide. According to Bur- 

 meister's figure of G. asfer"^ the same bone had a width of about 

 132 mm. Burmeister's figur^ indicates that the front end of this 

 vertebral tube, in the region of the articulations of the third, fourth, 

 and fifth pairs of ribs, was bounded on each side by a ridge ; but in 

 the specimen here described there are here no such ridges. However, 

 further backward these ridges become very prominent. Again, the 

 median ridge, composed of the coalesced spinous processes, which 

 in Burmeister's figure is still prominent opposite the tenth and 

 eleventh pairs of ribs, is obsolete in G. petallferus. The rear of the 

 twelfth vertebra is rough and was joined to the first lumbar probably 



1 Burmeister, Anales Mus. Pub., Buenos Aires, vol. 2, pi. 30. ^ idem, pi. 30, flg. 1. 



