384 



PROCEEDINGS OF THE ACADEMY OF 



[May 



for the length of the bridge, thus making the plastron 440 mm. 

 long. 



•The anterior lobe (fig. 1) has been close to 200 mm. in width. 

 The interclavicle, or entoplastron, has had a width of 100 mm. ; its 

 length has probably been about 80 mm., but its hinder border is 

 missing. The gular scutes encroach on its anterior border. A 

 broad rounded lip has projected beyond the gulo-humeral sulci 

 about 28 mm. It has had a Avidth of 80 mm., and is not notched in 

 front. The whole border of the anterior lobe is acute, through the 

 beveling off of the upper side. Fig. 2 is a section through the lip 



Fii 



Fig. 5. 



at the midline, and shows this beveling. The greatest thickness at 

 the lip is 23 mm. ; at a point halfway to the axillary notch this 

 thickness has been reduced only to 21 mm. ; near the notch it is 

 about 10 mm. Superiorly the lip extends back about 50 mm. 

 From the summit of the lip two ridges, with a shallow valley 

 between them, run toward the axillary notch, diverging gently. 

 There has evidently been no thoracic excavation beneath the lip 

 behind. Such an excavation is found in T. laticaudata, T. hexa- 

 gonata and in the living T. polyphemus. 



The posterior lobe (fig. 3) has been broadly notched behind, the 

 notch having a width of about 90 mm. and a depth of 85 mm. 

 The terminal lobules are direcled outward and upward, somewhat 



