BAENID&. 73 
pendicularly, while the horizontal diameter is only 14 mm. The narial opening ts 21 mm. wide 
and it looks strongly upward as well as forward. The bones roofing it are 6 mm. thick. The 
tympanic region 1s damaged, but the vertical diameter was 20 mm. The quadrate is deeply 
notcht for the passage of the stapedial rod. 
At their narrowest part the pterygoids are 14 mm. wide. There are large postpalatine 
foramina. The front of the choane is placed 17 mm. behind the premaxille. The cutting- 
edges of the maxille converge at nearly right angles. The triturating surface is 7 mm. wide. 
At its inner border, on each side of the choanz, arises a sharp crest. These crests converge to 
the front of the choana, then run parallel to near the premaxille, thus producing a deep 
groove in front of the choanz. 
The lower jaw (plate 14, figs. 5, 6) is thick and heavy. From the middle of a line joining 
the front borders of the articulation for the quadrates to the tip of the jaw is 4o mm. This line 
prolonged backward even with the extremities of the rami would measure about 52 mm. while 
the greatest width was 60 mm. The triturating surfaces are concave transversely, and are 7 
mm. wide. The middle of each ramus is 9 mm. thick and 15 mm. high. The tip of the jaw is 
turned upward, beak-like. The length of the symphysis on the lower side is 21 mm. 
The upper surface of the skull was undoubtedly covered with numerous horny scutes. 
These are shown, as far as determined, in plate 13, fig. 1. They are somewhat irregular in 
form and disposition, but there is no difficulty in making out some symmetry in their arrange- 
ment. The horny covering of the maxilla appears to have been divided, for a deep sulcus runs 
downward from the front of the orbit to the cutting-edge. 
Fics. 54-56.—Baéna sima. No. 5907 A. M. N. H. 
54. Pelvis, right side. X}- 56. Digit. XX. 55- Distal end of humerus. 4. 
Accompanying the shell of this specimen are various portions of the internal skeleton, 
mostly fragmentary, however. The left humerus is represented by the proximal and the distal 
ends. The proximal shows a width, from the outside of the ulnar to the outside of the radial 
process, of 33 mm., a single millimeter more than in the specimen of B. arenosa, No. 5973, 
above described. Nevertheless, the long diameter of the head is 14.5 mm.; that of No. 5973, 
13mm. The ulnar process has a thickness of 11 mm.; that of No. 5973 a thickness of g mm. 
The distal end of this bone is 27 mm. wide. The trochlea has a narrow rounded ridge for the 
head of the radius and a broader one for the head of the ulna, the two being separated by a 
groove. Above the trochlea is a deep olecranon depression. The prepubic process resembles 
that represented in fig. 86, but it is thin and flat. With this specimen are found 3 conical dermal 
bones whose bases were buried in the skin, the remainder being covered with horn. Two ot 
these are symmetrical and may have been placed on the midline of the upper side of the tail, as 
in Chelydra. However, they are not comprest, but circular in section. The base of one is 10 
mm. in diameter and the height is the same; the other is smaller. The third is unsymmetrical 
and somewhat flattened. It 1s possible that on the tail were 3 rows of dermal bones or there 
may have been dermal bones on the legs, as in some species of Testudo. 
No. 5965 may be regarded as the paratype of the present species. It furnishes only the 
carapace and plastron. It was secured in 1903, at Grizzly Buttes, Wyoming. The carapace is 
more complete than that of the type and has furnisht plate 15. The length is 333 mm. along 
