460 



FOSSIL TURTLES OF NORTH AMERICA. 



subacute free border of the lip the bone rises on the upper side to a point 105 mm. behind the 

 front and then drops off suddenly. The greatest thickness attained is 70 mm. The upper 

 surface of the lip is convex. There is no conspicuous notch where the gulo-humeral sulcus 

 crosses the border. 



The entoplastron was about 245 mm. wide. Its length is conjectural. It was pointed in 

 front. Its greatest thickness at the midline is 70 mm., while the thickness of the hyoplastron 

 is 46 mm. 



The hinder lobe (fig. 617) had a length of about 160 mm. along the midline and a basal 

 width of about 530 mm. Posteriorly there is a median notch 220 mm. wide and only 45 mm. 

 deep. At the inguinal notch, on the upper surface of the lobe, a great wall begins and runs 

 backward along the free border. The outer face of this wall is perpendicular and, at the 

 notch, 100 mm. high. At the femoro-anal sulcus the height is 40 mm., and the outer face is 

 inclined at an angle of about 45 . From the beginning the inner face slopes at an angle ot 

 about 45 . 



Figs. 618-620. Tt-studo crassiscutata. Neurals and costals. Xj. 

 618. Third and fourth neurals. 619. Costal bone. 620. Costal bone. 



In the U. S. National Museum is a collection of fossil tortoise bones, No. 4963, which were 

 collected near Tampa, Florida, by Mr. A. M. Lambert. They are believed to belong to this 

 species. There are 2 successive neurals, the third and the fourth (fig. 618). They are remark- 

 able for their size and great thickness. The third has a length of about 1 10 mm. and a width 

 of 155 mm. It is crost by a deep sulcus. From each end of the bone the surface slopes toward 

 this sulcus, so that the bottom of the latter is 15 mm. below the level of the ends of the bone. 

 The fourth neural, like that of most other species of the genus, is much larger than the third 

 and is octagonal in form. Its length is 130 mm.; its width, 200 mm.; and its thickness, 44 

 mm. Each side was in contact with the third, fourth, and fifth costals. An estimate makes it 

 probable that the carapace of this individual was about 4 feet in length. 



Fig. 619 represents the proximal end of a costal belonging to this collection, either the third 

 or the fifth. Its greatest width is 150 mm., but at the distal end of the fragment the width is 

 reduced to 1 1 1 mm. At the proximal end the thickness is 40 mm. Here it was in contact with 



