56 FLORIDA GEOLOGICAL SURVEY-EIGHTH ANNUAL REPORT. 
the species called Tcstudo atascosae (Hay, Foss. Turtles N. A., 
p. 464, figs. 627-628) must be known as Gopherus atasaosae. 
This xiphiplastral bone resembles that of G. atascosoe, , There 
are, however, numerous differences. The width of the xiphiplas¬ 
tral part of the hinder lobe in the types of the two species is nearly 
the same, 158 mm. and 168 mm. In G. praecedens the distance 
from the bottom of the posterior notch to the outer end of the 
hypo-xiphiplastral suture is 92 mm.; in G. atascosae it was about 
no mm. This comes about from the fact that the xiphiplastron 
of the former species, including the ear-like lobules, is shorter. In 
the type of G. atascosae it had a length of 100 mm.; that of G . 
praecedens is only 83 mm. long. In G. praecedens there is a wall¬ 
like thickening of the bone along the outer border not greatly un¬ 
like that of G. atascosae (op. cit. fig. 628a) ; but while this is 30 
111m. high in the last named species, in G. praecedens it was only 
21 mm. The section taken through the ear-like lobule of the bone 
appears to have been about the same in the two species (op. cit. 
fig. 628b) and the thickness seems to be closely the same, 22 mm. 
The thickness of the bone forming the type of G. praecedens, 
measured at the middle of the anterior border, is 8.5 mm. The 
portion which forms the hinder lobule and which on the lower side 
is occupied by the anal scute appears swollen downward, project¬ 
ing several millimeters below the rest of the bone. This anal area 
is finely pitted, while the surface of the remainder of the bone is 
smooth. 
Gopherus praecedens probably resembled the species yet exist¬ 
ing in Florida more than it did the extinct Texas species referred 
to above. The males of G. polyphemus have the lobules of the 
rear of the plastron swollen on the under surface, as they were 
in G. praecedens. The xiphiplastral bone of G. polyphemus is, 
however, somewhat narrower, as compared with the length; its lat¬ 
eral border is far less deeply notched; the outer face of the border 
of the bone, at the suture with the hypoplastral is perpendicular, 
even overhanging, instead of sloping upward and inward, as it 
does in G. praecedens; and the border of the bone in the hinder 
notch is much more acute than in the fossil species here described. 
No other bones are present which can be with certainty re¬ 
ferred to this species. 
