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Trachemys trulla sp. nov. 
Plate 56, figs. 2-6; text-fig. 453 
The type of this species is No. 3934 of the American Museum of Natural History. It con- 
sists of portions of both epiplastra of a specimen which accompanied the type of Dr. Leidy’s 
Emys (Trachemys) petroler; and was therefore obtained from the Pleistocene deposits of 
Hardin County, Texas. Without additional materials it is not possible to determine with 
exactitude the generic relations of the species, but the parts resemble most those of Trachemys 
elegans, a present inhabitant of that region of the country. 
The bones forming the type are Albee exactly the size of those of a specimen of 7. elegans 
whose length of carapace is 240 mm. From the latter it differs in having a much narrower lip, 
that of 7. elegans being 59 mm. wide, that of 7. trulla, 41 mm. wide. The lip of the latter 
(plate 56, figs. 2, 3) is also of a somewhat different form. In 7. elegans, seen from aboye, the 
gulo-humeral sulci are directed outward and forward to the border of the epiplastral bones, 
the lip projects rather abruptly, and it is subtruncated. In 7. trulla each gulo-humeral sulcus, 
= on the upper surface of the bone, runs directly forward, the lip 
{ 4 es projects gradually from the border of the bone, and rounds for- 
ward di inward to the midline. The free border of the lip of 
< T. elegans is usually, if not always, dentated; that of 7. trulla is 
yy j all) ) 
Da smooth in outline. 
vA ft The lips of both 7. elegans and of T. trulla are excavated on 
3 the upper surface so as to resemble somewhat the spout of a 
t pitcher. In 7. trulla the sides of this spout descend more 
i _ abruptly than in the case of the observed specimen of 7. elegans. 
=e These sides rise each as a ridge some distance above the level of 
; ————--— the gulo-humeral sulcus and parallel with it. Anteriorly each ridge 
i descends into the free border of the lip. At the hinder end of each 
{ ridge, at a lower level, is a deep pit. 
At the midline on the upper surface the gular scutes extend 
backward a distance of 15 mm. At the hinder end of the epi- 
plastron the width of the humerals was about 15 mm. 
Seen from below, the middle of the lip descends little below 
the general level of the epiplastral bones. The gulo-humeral sulci 
are deeply imprest and they extended backward on the entoplas- 
tron. The length of the sulcus separating the gulars was 32 mm. 
The suture between the two epiplastrals has a length of 27 mm. 
The thickness of the bones at the symphysis is 7mm. The free 
border of the epiplastron, where it joins the hyoplastron, is acute; 
Fic. 453.—Trachemys trulla. °° each side of the gulo-humeral sulcus, thickened and rounded; 
Plastron restored from Near the midline, again acute. 
bones figured on plate 56. With the bone described above are a right hyoplastron, a 
right hypoplastron, and a left xiphiplastron which are supposed 
to have belonged to the same species. These bones are represented by figs. 4, 5, and 6 of 
plate 56. 
Text-fhg. 453 is a restoration of the plastron, made up from the various bones that are 
described above. 
This figure shows the relative dimensions of the bones and the positions of the scutes. 
Fig. 4 of the plate cited presents a view of the upper surface of the hy oplastron, fig. 5 of the 
hypoplastron, and fig. 6 of the xiphiplastron. The relative width of the beveled ace on 
the upper side of thee bones is displayed. All the free borders are acute, especially that of the 
xiphiplastron. The notch at the rear of the hinder lobe was broad, but very shallow. The 
hyoplastron is 7 mm. thick on the midline, at the middle of the length. The anterior end of 
the hypoplastron, on the midline, is 7 mm. thick; but further backward becomes 10 mm. The 
anterior end of the xiphiplastron, at the summit of the bevel, is 7 mm. thick. The bones are 
not sculptured, 
