20 



PROCEEDIls'GS OF THE NATIONAL MUSEUM 



VOL. 86 



Lower jaws. — The sutures in the three rami under consideration are 

 clearly determinable, but the arrangement and extent of the separate 

 elements show no characteristics that would in any way distinguish 

 them from the other species of the genus. Since the structure of the 

 ramus in Glyptosauni^s has been quite fully described ^ it is unneces- 

 sary here to enter into further details. 



Table 2. — Measurements of skulls and jaws of Glyptosaurus giganteus 



Measurement 



U.S.N. M. 

 no. 13861 



U.S.N. M. 

 no. 13869 



Skulls 



Greatest length of skull, about 



Greatest width of skull, across parietal 



Greatest width of skvill, between orbital borders. 



Greatest height of skull 



Greatest height of skull with mandible 



Anteroposterior diameter of orbit 



Vertical diameter of orbit 



Jaws 



Greatest length of ramus, about 



Depth of ramus at posterior end of tooth row 



Depth of ramus at anterior end of tooth row 



Depth of ramus posterior to coronoid 



Transverse width middle of tooth series 



Transverse width between coronoid and cotylus 



Greatest transverse diameter across articulated rami. 



Mm 



128 

 54 



34. 5 

 41. 5 

 58 

 24 

 20.5 



112 

 15 



A/m 



58 

 36 



12 

 9.5 

 15 



60 

 24 

 19 



108 

 14 



6 

 11 

 11. 5 



3 

 56 



Dermal scutes. — The osseous dermal scutes of Glyptosaurus that 

 surround the neck and anterior part of the body are beautifully 

 preserved in U.S.N.M. no. 13869 (see pi. 1). These are arranged in 

 transverse and longitudinal rows, parts of 15 transverse rows being 

 present in this specimen and little disturbed from their normal place- 

 ment. The transverse rows of rectangular scutes immediately pos- 

 terior to the skull cover the dorsal surface, the right side, and the 

 region under the throat. More posteriorly, however, the scutes are 

 missing on the ventral surface, as are most of those on the left side. 

 With the exception of the scutes forming the median dorsal row, the 

 others are nearly all rectangular in shape. The first two rows pos- 

 terior to the skull are about as long as wide, whereas those that 

 follow are nearly twice as long as wide. The scutes are closely 

 joined by their lateral edges, and their ends are imbricated, the extent 

 of the imbrication indicated by a smooth transverse band across their 

 anterior ends. In the few scutes Avhere the anterior end is exposed 

 this smooth band is very narrow, measuring about one-sixth the total 

 length of the scute. It is quite evident that this overlap is much 



•Mem. Nat. Acad. Sci., vol. 22, pp. 110, 111, 1928. 



