341 



region is not at all serrated; but it is somewhat flared upward. The surface of the shell is 

 smooth. The sulci are narrow but rather deeply imprest. 



The neural plates are in general hexagonal, with the broad end forward. The second to 

 the fifth, inclusive, have the anterior end more or less concave. Most of the neurals are longer 

 than broad, but the posterior are broader than long. The table herewith gives the dimensions 

 of the neurals. 



Dimensions of ueurals. 



Eimensions of vertebrals. 



The nuchal is 68 mm. long, 50 mm. wide at the free border, and has a maximum width of 

 80 mm. The first suprapygal is 33 mm. long and 29 mm. wide; the second 42 mm. long and 

 90 mm. wide. The pygal has a length of 30 mm. and a width of 40 mm. The free border of 

 the nuchal and the first peripherals is acute. 



The peripherals are high. In front, they extend upward above the margin of the shell 

 about 46 mm.; laterally about 62 mm.; at the inguinal notch, about 70 mm.; the most 

 posterior, about 28 mm. 



All the vertebral scutes are longer than broad, except the fifth. The first is unusually 

 narrow. The sides of the median three are bracket-shaped. The dimensions are given in the 

 middle table above. 



Besides the nuchal scute, there are on each side the usual 12 marginals. These do not rise 

 to the upper borders of the peripheral bones. The nuchal scute is very narrow, only 14 mm.; 

 its length is 16 mm. The dimensions of the marginals are shown in the table above. 



The plastron (plate 52, fig. 2; text-fig. 448) has a total length of 410 mm. The anterior 

 lobe is 1 16 mm. long and 174 mm. wide. The posterior lobe is 135 mm. in length and 198 mm. 

 in width. The bridge is 155 mm. wide. The anterior lobe is slightly contracted just in front 

 of the axillary notch; then expands a little to the ends of the epiplastra; then curves slowly 

 to the truncated lip. The latter is unusually narrow, having a width of only 38 mm., being less 

 than one-fourth of the width of the anterior lobe. It is markt outwardly on each side by a stout 

 tooth, mesiad of which there is a notch. In the latter are three smaller teeth. On the upper 

 side of the bone there is, along the midline, a prominent ridge, 48 mm. long and bounded on 

 each side by a valley, the latter opening in front at the notch of the lip. At the hinder end of 

 the ridge is a transverse ridge, which passes outward and backward. About the middle of its 

 length the epiplastron has a thickness of 15 mm. 



The length of the entoplastron is 72 mm.; the width, 74 mm. The hyoplastra are 94 mm. 

 along the midline, and each extends laterally about 104 mm. The hypoplastra join along the 

 midline for a distance of 100 mm. The xiphiplastrals meet along the midline 85 mm. The 

 notch between their hinder ends is 15 mm. deep; the distance between the tips is 34 mm. 



There are the usual scutes on the plastron. The gulars, taken together, are 64 mm. wide 

 in front. They extend backward well on the entoplastron, their median length being 72 mm. 

 The humerals meet along the midline for a distance of 35 mm. The pectorals encroach on the 

 entoplastron. The suture between them is 74 mm. long. The abdominals extend along the 

 midline for no mm. The femorals are only 38 mm. fore and aft at the midline; but 93 mm. 

 at their outer ends. The anals occupy 66 mm. of the midline. On account of some crushing 

 the axillary scute can not be made out. It is certain, however, that it failed by at least 25 mm. 

 to reach backward to the fifth marginal. The inguinal scute lackt about 27 mm. of extend- 

 ing forward to the sixth marginal. 



