EMYDIDZ. 
Us 
Wn 
at the costo-vertebral sulcus. The third left peripheral (fg. 3) has a length of 32 mm. along 
the tree border, and a height of 30 mm. ‘The extreme width of the face which j joins the second 
peripheral is 20 mm. 
Fig. 4 of the plate cited illustrates the tenth left peripheral. It is 21 mm. along the acute 
free edge, 35 mm. high, and it has a maximum thickness of 7mm. The uppel surface is con- 
cave up and down and slightly convex fore and aft. It doe not appear to have formed a 
jagged suture with the contiguous ends of the costals. 
The dimensions of some : the scute areas can be only approximately determined. The 
nuchal scute has a length of 17 mm. and a width of 10 mm. The anterior end of the first 
vertebral has a width of 37 mm. The anterior end of the fourth vertebral scute ov erlapt the 
fifth costal bone a distance of 17mm. Its width was therefore 34 mm. plus the as yet unknown 
width of the neural, amounting to probably 45 mm. 
The sculpture of the carapace may now be briefly described. On the nuchal bone the area 
occupied by the first vertebral scute is ornamented with longitudinal ridges, 5 in a line 10 mm. 
long. These ridges are more or less interrupted by the grooves concentric with the anterior 
border of the scute. On the area of the first marginal scute the ridges diverge at an angle 
with the midline and are interrupted by grooves parallel with the hidlifie: The distal hale of 
the third costal is markt by ridges running downward and obliquely toward one edge of the 
bone. These again are crost by ridges parallel with the distal end of the bone. The fifth 
costal 1s similarly sculptured on the distal end, but the ridges are more irregular. The middle 
third has, along the anterior border, some strong ridges anid grooves at right angles with the 
sutural border, while the hinder half 1s occupied by conical elevations having little regularity. 
On the third peripheral bone the area above the costo- 
marginal sulcus is markt by midges running downward; 
the area in front of the intermarginal sulcus ‘shows strong 
ridges and grooves directed forw ard; while the area behind 
wen? : this sulcus presents narrower and closer ridges, broken by 
cross furrows. ‘The hinder peripherals have the area in front 
\ —s of the descending sulcus markt by both vertical and hori- 
woe zontal ridges; while the posterior half presents coarse ridges 
that run downward and backward. 
The plastron possest an anterior lip (hg. 454) whose 
width was 54 mm. Its free borderis subacute. On the 
upper side of the lip the horn-covered area extends backward 
a distance of 15 mm. Where the bone joined the entoplastron 
the thickness is 10 mm. The gular scutes overlapt the entoplastron. 
The hypoplastron (plate 57, fg. 5) is 72 mm. long, and it had a width of 55 mm. at the 
inguinal notch. At the midline, near the anterior end, the bone is 13 mm. thick. The free 
border of the bone is acute. The horn-covered band on the upper surface is 22 mm. wide at 
the hypoxiphiplastral suture. 
The area occupied by the gular scutes is ornamented with ridges and grooves which are 
nearly parallel with the gulo-humeral sulcus. The markings on the area of the humeral scute 
are indistinct. The hypoplastron is distinctly sculptured. On the area of the abdominal scute 
are short vermicular ridges, reminding one of the carapace of a trionychid. On most of the 
area of the femoral scutes the sculpture suggests a tiled roof; but on the outer half there 
are distinct longitudinal ridges, 7 of them in a line to mm. long. 
Fig. 6 of plate 57 shows the left first costal of a smaller individual. It is markt by radiating 
and concentric grooves and ridges. On the inner surface is an excavation for the inguinal 
buttress. This buttress rose about 15 mm. above the lower border of the bone. 
This species differs from the living 7. scripta and T. elegans in the form of the nuchal bone 
and the scutes overlapping it and in having had no notches in the borders of the carapace. 
The nuchal here described has a good deal of resemblance to that on which Pseudemys 
extincta is based. The latter nuchal is that of a considerably larger specimen and is much 
smoother, the sculptural ridges having much less elevation. The nuchal scute, too, is longe: 
relatively to the length of the bone. P. concinna has narrower nuchal and first vertebral 
scutes. The same is true of P. rubriventris. 
Fic. 454.—Pseudemys celata. Left 
half of lower surface of plastral 
lip of type. X%. U.S.N.M. 
