TOXOCHELYID&. 165 
are 3 others joined in their natural relation, and 3 more joined together and the hinder- 
most united with the suprapygals. The single neural must belong in front of all the others. 
It can not be the first one, because it is too thick in front for the nuchal, in case this was as 
thin behind as in the genus generally; also because it is not crost by the sulcus separating the 
first from the second vertebral scute. It can hardly be anything else than the second neural. 
At the hinder end of the upper surface there is a half-facet for another bone, one of the series 
of ossicles mentioned above. The neural which is regarded as the third has on its anterior 
end a half-facet which completes the one on the supposed second neural. Behind this facet 
is a sulcus, believed to be the one which divides the first from the second vertebral scutes. 
The fourth neural has no tubercle of its own, but its hinder end supported a small part of 
the tubercle which belongs to the fifth neural. This tubercle has a length of 20 mm. Behind 
it is the sulcus which passes between the third and the fourth vertebral scutes. The tubercle 
is wholly co-ossified with the bones on which it rests, but there are traces of the sutures. The 
sixth neural is sharp along the midline, while its sides slope steeply, like a high-pitcht roof. 
The seventh neural is short and closely joined to the eighth. A long and strongly comprest 
tubercle occupies nearly the whole length of both these neurals and appears to be co-ossified 
with both, only traces of the sutures remaining. 
The suprapygals are co-ossified. The first is sharply rooft, while the next one has a rather 
high and comprest tubercle. The anterior suprapygal appears to have been expanded on 
- = ______ each side, but the expansions are broken away. The sulcus 
between the fourth and the fifth vertebral scutes doubtless 
Element. Length. Width. : 
| ate crost behind the tubercle on the second suprapygal. The 
| pygal is represented in plate 30, fig. 1. Its height is 14 mm.; 
an ae ef F its width from side to side, 27 mm. Its upper, or anterior, 
Rass 18 2B border appears to have articulated with a suprapygal which 
| aS 28 24 isnow missing. The upper surface of the pygal is longitudi- 
oe a z os nally grooved, while the inferior has a more extensive longi- 
Sie eodlesetnie: 10 15 tudinal channel. This pygal is quite different from that 
Ist suprapygal.. . 24 - of the type of I. stenopora. The dimensions of the neurals 
2d suprapygal.... 31 13 
and suprapygals are shown in the accompanying table. 
It is evident that there were 11 pairs of peripherals, as 
in most turtles. The two anterior are narrow and thin. These are followed by 4 others which 
are thicker and broader, and these again by others which are thin. The table gives the 
dimensions of the peripherals present. The width is taken at the front end. 
The anterior end of the first peripheral is oblique for articulation with the nuchal. The 
third and the succeeding peripherals to the ninth inclusive have each a pit for a corresponding 
rib-end. The tenth has no pit. The eleventh is not present. Since the hinder end of the 
tenth peripheral is 19 mm. wide and the articular end of the pygal only 12 mm. wide, it follows 
that the eleventh was considerably wider at one end than the other. All the peripherals are 
crost by shallow sulci. 
Dr. Wieland has represented (Amer. Jour. Sci., XX, 1905, p. 335, fig 6; here reproduced 
as fig. 229) the rib-end of the eighth costal as entering a pit in the anterior end of the eleventh 
peripheral. The end of the rib was not present and it is 
Width 
ae stated that the rib-pits are all small. In the specimen 
Peripherals.| Length. i; Thickness. ea : : = 
upper face. ficured by Dr. Case (Univ. Geol. Surv. Kans., 1v, 1898) 
5 . y . 
: ee is the eighth costal comes down to a thin edge and there 
2 26 ir “ appears to have been no rib-end. Moreover, Case states 
3 30 8 12 that the eleventh peripheral has no groove nor pit for a 
ee S F Pr rib. At my request Dr.C. E. McClung, of the University 
S ) * -T7 ‘ * « = n r 
6 38 15 10 of Kansas, examined this specimen. He finds the pygal 
36 i : and the eleventh peripheral in their natural positions and 
32 i . ‘s - 
9 a a Be the eighth costal with a sharp border and no trace of a 
Io 32 16 75 rib. Case is probably in error in representing the rib of 
the seventh costal plate as going to the tenth peripheral. 
The plastron appears to have resembled quite as much that of the Cheloniidz as it did that 
of Chelydra. As in the former family, that part of the plastron which lay between the fore and 
