TKSTUDINIDA:. 



38 1 



midline to the lower ends of the peripherals, is about 220 mm. The extreme width of the car- 

 apace was about 550 mm. From a line joining the axillary and inguinal notches the bridge 

 ascends at an angle of 30, altho this may have been greater during life. About 130 mm. beyond 

 the line mentioned there is an abrupt turn of the carapace upward. This continues, in our 

 specimen, to the upper margin of the peripherals, a distance of 135 mm. The abrupt turn men- 

 tioned marks the position of a sharp carina which runs along the side of the shell from the free 

 border of the carapace in front of the bridge to the free border behind it. Such a carina is seen 

 in at least some specimens of H. corsoni. The width of the bridge is 250 mm. 



The hinder half of the plastron was very concave, especially from the inguinal notches 

 backward. The anterior half was flat. The individual was probably a male. 



The bone of the central portions of the plastron is thin, 17 mm. just behind the ento- 

 plastron, in the midline; 9 mm. at the suture between the hyoplastrals and hypoplastrals; 



and 8 mm. at the anterior end of the xiphiplastrals. 

 Near the free borders, however, the bone is very 

 thick, 31 mm. at the anterior end of the epiplas- 

 tron, 37 mm. at the anterior end of the xiphiplas- 

 tron. On the epiplastron the bone is beveled off 

 gradually to a sharp edge. Behind the inguinal 

 notch the bone is beveled off very abruptly, so 

 that the beveled portion is nearly perpendicular. 

 The hinder end of the xiphiplastron is 32 mm. 

 thick, rough, and with a broad, rounded edge. 



No part of the entoplastron is present, but 

 the sutural border of the epiplastron enables us 

 to determine something regarding its extent and 

 form. It had a breadth of 156 mm. at the hinder 

 ends of the epiplastrals. From a line joining 

 these it has extended backward about 75 mm. 

 From this we may infer that its larger portion lay 

 behind the ends of the epiplastrals. It was not 

 crost by the humero-pectoral suture. The ante- 

 rior end of the hyoplastron, where it articulated 

 with the epiplastron, is 55 mm. wide. The extreme 

 length of the hyoplastron is 222 mm.; its length 

 in the midline is 155 mm. The length of the 

 hypoplastron in the midline is 140 mm.; on the 

 line joining the axillary and inguinal notches, 173 

 mm. At the midline the xiphiplastrals measure 

 1 18 mm. At their anterior ends they are 140 mm. 

 wide. The notch at the posterior end of the plas- 

 tron has not exceeded 25 mm. in depth. 



The suture between the plastron and the per- 

 ipheral bones, on the bridge, runs a very sinuous 

 course, the opposing bones forming broad inter- 

 digitations 35 mm. long. The fifth and sixth 



FIG. 480. HaJnanus tumidus. Plastron, 

 lacking epiplastron and entoplastron. Xi. 

 No. 2090 A. M. N. H 



peripherals are each about 85 mm. wide, fore and aft, and rise about 135 mm. above the turn 

 of the carapace upward. 



The plastral buttresses of this species are rather weak, but are relatively better develop! 

 than in Testudo. They rise to the upper margin of the peripherals. The sulci are deeply 

 imprest. The humero-pectoral begins just in front of the axillary notch, runs inward and back- 

 ward for a short distance, then straight across the plastron, just missing the hinder border of 

 the entoplastron. Behind this sulcus, 55 mm., the pectoro-abdominal sulcus crosses the mid- 

 line. It is bent slightly forward on each side, then runs outward, backward, and upward to 

 the marginal suture. The abdominal scutes have great extent. Along the midline they measure 

 193 mm. The sulcus limiting them posteriorly runs from the midline outward and somewhat 

 forward, passing 50 mm. in front of the inguinal notch. The femoral scutes join along the 



