Il8 FOSSIL TURTLES OF NORTH AMERICA. 



The first vertebral scute had a length of about 90 mm., a width of about 140 mm. in front 

 and of about 80 mm. behind. The approximate proportions of the next three are shown in the 

 restoration. 



Cope figured (Ext. Batr.,Rept., etc., p.l6o, fig. 43) a considerable part of the anterior lobe 

 of the plastron. Another portion of the same specimen has been found, the border of the left 

 axillary region, and this is included in fig. 116. This specimen suffices to give us a clear idea 

 of the form of the anterior half of the plastron. This lobe had a length of about 135 mm. and 

 a width of about 260 mm. It was rounded in front, with a slight median concavity. The free 

 edges are obtuse, except at the union of the epiplastrals with the hyoplastrals. The thick- 

 ness is everywhere close to 10 mm. The entoplastron was diamond-shaped, 65 mm. long and 

 86 mm. wide. The suture of the hyoplastron with the hypoplastron was oblique to the surfaces 

 of the bones, so that the hyoplastron overlaps the hypoplastron somewhat. A portion of the 

 axillary region is preserved. The base of the buttress did not extend far within the free border 

 of the anterior lobe. 



It is unfortunate that the epiplastron is not complete to the midline, for we are left in some 

 doubt regarding the more anterior scutes. An intergular occupied a large part of the entoplas- 

 tron. Cope represented this as overlapping some distance on the epiplastrals, but it seems to 

 the writer that a sulcus crosses the entoplastron close to its anterior border. Probably the 

 gulars met, possibly coalesct, at the midline, in front of the intergular. The humerals occu- 

 pied the hinder half of each of the epiplastra. In some specimens of this genus there seems to 

 be a scute cut off from the inner end of each gular. Such a scute, or such scutes, would be 

 without name. Better specimens are required to settle this matter. The arrangement of the 

 scutes in this region appears to resemble that of Chelodina. The pectorals measure 87 

 mm. along the midline; the abdominals occupy the posterior 26 mm. of the hyoplastra. 



Cope presents a figure of the hinder half of the plastron of this specimen. It is difficult to 

 determine just how much of that part of the plastron was in his hands. At present there is 

 with the specimen only a fragment of the left inguinal region, a fragment of the left xiphiplas- 

 tron, and the hinder angle of the right xiphiplastron. The latter is marked in Cope's figure 

 with the letters Is. The fragment of the inguinal region extends forward to the suture with 

 some bone, probably the mesoplastron. On the upper surface about 40 mm. behind this 

 suture is a prominent ridge, the base of the inguinal buttress. This ridge is much more 

 strongly developt than in T. longinuchus. 



The base of the xiphiplastron presents a coarse suture with the hypoplastron. The free 

 border of the bone is acute. From the edge the bone thickens to 12 mm. On the upper 

 surface of this bone is a part of the much elevated and rough articulating surface for the pubis. 

 On the hinder angle of the xiphiplastron is the circular elevated and rough surface for articu- 

 lation with the ischium. The notch in the rear of the plastron was about 140 mm. wide. 



On the anterior half of the plastron there is little evidence of sculpture. It is more conspic- 

 uous on fragments of the hinder half, where it consists of a network of grooves. 



Cope mentions a specimen of this species from Hornerstown, New Jersey, which displayed 

 the mesoplastral bones. These presented a rounded interior outline and were applied to an 

 equal extent of the hyoplastrals and the hypoplastrals. They reacht one-third the distance 

 toward the midline. The plastron was 10.5 inches between the inguinal notches. The speci- 

 men is now lost. 



Another specimen, No. 1343 of the American Museum, an individual a little larger than 

 the type, shows a portion of the right hyoplastron from front to rear. The length is 170 mm. 

 Just behind the axillary buttress the posterior sutural border makes a turn forward at nearly 

 a right angle. It appears evident that this was to receive the mesoplastron. No. 1474 of 

 the American Museum, a part of the Cope collection of fossil reptiles, was obtained by Cope, 

 February 22, 1871, and therefore not mentioned in his monograph of 1869 and 1870. It 

 came from Birmingham, Burlington County, New Jersey. It furnishes, besides some fragments 

 of costals, a large part of both hypoplastra and the complete left xiphiplastron (figs. 117, 118). 

 The individual was of almost exactly the same size as the type. The distance along the median 

 line, from the hyohypoplastral suture to the bottom of the notch in the rear, is 243 mm. The 

 left hypoplastral came into contact with the right xiphiplastron, an irregularity not uncommon 

 in the early turtles. The right hypoplastron is 115 mm. long; the left xiphiplastron, 105 mm.; 



