NO. 2147. Tiro EXTINCT 2IAJ,BIALS FR02I TEXAS— HAY. HI 



In G. petaUferus the second tooth (pi. 3, figs. 2, -1) is different 

 from the fourth. Its length is 20 mm., its width only 9 mm. The outer 

 ends of all the lobes are much reduced. It resembles considerably 

 the first tooth of G. asper. The first tooth is missing in the Texas 

 species, but the inner wall of the socket is present. From this it is 

 evident that the lobes were much reduced on the inner side also. It 

 is pretty certain that this tooth was thin and simple in construction, 

 but the length of its grinding surface nearly equaled that of the 

 second tooth. 



The lower teeth were nearly straight, as shown by the one present 

 and by the sockets in the fragments of the lower jaw. The one 

 present (pi. 3, fig. 5) had a height of 75 mm., a length of 21 mm. 

 on the grinding surface, and a width of 12.5 mm. on the middle lobe. 

 The tooth present, belonging on the right side, is placed opposite 

 the front border of the ascending ramus and is probably the sixth 

 in the series. There were at least two others behind it. In G. asper^ 

 as figured by Burm.eister, the grinding surface of this tooth has a 

 length of 21 mm. and a width of IG mm. across the middle lobe. 

 In G. petalifei-us the length is 21 mm., the width 13 mm. In the 

 tooth of this species the axes of the lobes are little turned from a 

 perpendicular to the longitudinal axis; in G. asper they are much 

 more strongly deflected. 



In all the teeth, upper and lower, the central core of vasodentine 

 which sends lateral branches into the lobes undergoes secondary 

 divisions there, as in G. asper. 



The atlas is missing. In the giyptodonts the axis and the suc- 

 ceeding three or four cervicals are consolidated into one mass. 

 Usually in the genus Glyptodon the mass includes the sixth cer- 

 vical, but from Burmeister's description ^ it seems that in two species 

 it is sometimes free and sometimes confluent. In the specimen at 

 hand the sixth was evidently free and is missing from the collection. 

 The consolidated second to fifth vertebrae (pi. 3, fig. 6) are injured 

 somewhat; especially, the transverse processes are gone. The mass 

 resembles much that of the forms figured by Burmeister. From the 

 outside of one lateral articular surface for the atlas to that of the 

 other is 80 mm. Hence the bone is smaller than any of those figured 

 on the plate just cited. The distance from the outer side of one 

 postzygapophysis to that of the other of the fifth vertebra is like- 

 wise 80 mm. The height of the neural spine above the floor of the 

 neural canal is 63 mm. 



Judging from the character of the surfaces by which the sixth 

 cervical was united with the seventh, there was not much motion 

 between them. 



1 Anales Mus. Pub., Buenos Aires, vol. 2, p. 296, pi. 29. 



