72 FOSSIL TURTLES OF NORTH AMERICA. 
38 mm. long and 15 mm. high. The seventh, lying below the hinder half of the second costal, is 
56 mm. long and it rises about 36 mm. above the free border of the shell. On account of the 
obtuse border over the bridge the elevation of the lateral scutes is difficult to estimate. 
The plastron (fig. 53) is 320 mm. long. The anterior lobe is 92 mm. long, 112 mm. wide 
at the base, and 80 mm. wide at the gulo-humeral sulci. The bridge has a width of 138 mm., 60 
per cent. of the length of that part of the plastron behind the axillary notches. The hinder lobe 
is 92 mm. long, 127 mm. wide at the base, and g2 mm. at the ends of the femoro-anal sulci. 
The hinder border is slightly excavated. 
The mesoplastra are solidly co-ossifed with the contiguous bones, but some traces are 
found of the sutures. The bones appear to have been about 15 mm. wide at the midline. 
The forms of the various plastral scutes are shown in the figure. The course of the median 
sulcus is very tortuous and there are some irregularities in the others. The axillary region is 
damaged on both sides, but appearances indicate that there were 3 left inframarginals, the 
52. 53: 
Fics. 62 AND 52.—Baéna sima. Type. 1. Showing the form of carapace 
3 5 4 g P 
and plastron and the scute areas. 
52. Carapace. 53- Plastron. 
pectoral scute apparently having extended out to the marginals. There is a large inguinal 
inframarginal and another in front of it. There was doubtless an axillary scute, but the bones 
are missing which supported it. On the right side there were 4 inframarginals. 
The skull of this species (plate 13, figs. 1, 2; plate 14, fig. 4) is remarkable for its breadth 
and shortness. The premaxillary region is missing and likewise the condyle of the basioc- 
cipital; but the length from one to the other was very close to 64 mm. The breadth across the 
quadrates is 71 mm. From the quadrates the outline of the skull contracts rapidly to below 
the front of the orbits, where there is a sudden constriction. From this the outline contracts 
slowly, then rounds into the broad snout. The upper surface is convex. All the bones are 
solidly co-ossified, and no sutures are to be traced. 
The temporal foss are rooft over extensively, so that between the end of the short 
supraoccipital and the postero-lateral angles there is on each side only a shallow sinus. The 
interorbital space is 26 mm. wide. The orbits have their greatest diameter, 17 mm. directed per- 
