356 FOSSIL TURTLES OK NORTH AMERICA. 



Genus PSEUDEMYS Gray. 



Shell in general like that of Trachemys. Triturating surface of the upper jaw broad all 

 round, with a strongly developt tuherculated median ridge. Lower jaw with broad surface 

 and a median ridge; its lower surface flat. 



Type: Pseudemys rubrtventris Leconte. 



Pseudemys extincta sp. nov. 

 Plate 54, fig. 13. 



The basis of the present species is a nuchal bone belonging to the Jarman collection, the 

 property of Vanderbilt University. The collection was made in Hillsboro County, Florida, 

 from beds belonging probably to the Peace Creek formation. 



This nuchal is referred to Pseudemys because of its resemblance to that of P. rubrtventris, 

 of the Southern States. The hinder border is somewhat water-worn, but it evidently follows 

 closely the sutural edge. The median length is 62 mm.; the frontal width, 33 mm.; the 

 maximum width, 70 mm. The anterior border is acute. From this the bone thickens back- 

 ward about 30 mm., where is becomes 18 mm. at the midline, 15 mm. at the articulation with 

 the first peripheral. Where the bone joins the first neural it is 5 mm. thick. The nuchal scute 

 is 26 mm. long, q mm. wide in front, 19 mm. behind. The first vertebral is 48 mm. wide in 

 front, contracting behind this, then again expanding. 1 he first marginal has a length, fore and 

 aft, of 37 mm. Its union with the first costal on this bone is only 10 mm. long. 



The upper surface of this bone is in general smooth, but there are traces of a sculpture, 

 produced by the growth of the scutes. On the nuchal area the low ridges run parallel with the 

 midline; so also do those on the area of the first vertebral. Those on the areas of the first 

 marginals run outward and forward at an angle of about 45 with the midline. The ridges on 

 the areas of the first costals run outward and backward at a small angle with the midline. 



With the other bones from the region about Tampa Bay there come many portions of 

 plastrons, some of which probably belong to the present species. However, there is no way 

 for connecting any plastral lip, for instance, with any nuchal bone. The writer describes, 

 from that region, a number of species founded on nuchal bones, a quite characteristic part of 

 the skeleton. It remains for collectors and students to find and record other bones in their 

 natural association with these various nuchals. 



Pseudemys caelata sp. nov. 

 Plate 57, figs. 1-6; text-fig. 454. 



This name is based on some bones which belong to the U. S. National Museum. They 

 were obtained from "Mason's bone bed," somewhere in Levy County, Florida, and are 

 supposed, but not known, to belong to the Pleistocene epoch. They may belong to the Peace 

 Creek formation. The bones bear the LJ. S. National Museum's number 2508. They appear 

 to be parts of at least 2 individuals, one considerably larger than the other. Of the larger 

 individual there are present the nuchal; the distal end of the third costal, that of probably 

 the left side; the left fifth costal; the proximal end of the seventh right costal; the third left 

 peripheral; three posterior peripherals; the left epiplastron; and the left hvpoplastron. 

 Should it happen that more than one species is here included, the nuchal bone is to be regarded 

 .is the type. 



This species is conspicuous tor its sculpture, which resembles that of Trachemys senpta, 

 now living in the Southern States. 



I he nuchal bone (plate 57, fig. I ) is 45 mm. long and 23 mm. wide in front, and 55 mm. 

 wide where widest. The free border is acute; the greatest thickness, 10 mm. 



I he third cosr.il is 35 mm. wide distally and nearly 5 mm. thick at the sutural edge. The 

 fifth costal (tig. 2! is 25 mm. wide and 7 mm. thick at the costo-vertebral sulcus, and 32 mm. 

 wide at the distal end. The costo-vertebral sulcus crosses the proximal end at about 10 mm. 

 from the articulation with the neural. On the inner side of the distal half there is a prominent 

 ridge. In the lower end of this ridge is an excavation for the inguinal buttress. This buttress 

 rose about 20 mm. above the lower border of the costal. The seventh costal is 15 mm. wide 



