AND AVES OF NORTH AMERICA. 



103 



- ; 



penultimate and ultimate costals, covering tlieir sutural union, as indicated by sutural areas remaining. The penul- 

 timates are separated anteriorly by the round bono above mentioned; tlieir posterior united halves supported the first 

 supernumerary vertebral. The remaining two were beneath the last pair of costals. Pygal bone sub-triangular with 

 two obtuse ridges medio-anteriorly, and a slight projection laterally in front. This whole region is precisely like that 

 in T. suloatus. 



The iliac pit is much like that in T. suloatus, but the anterior bounding ridge is wanting for most of the length " the 

 distal extremity of the samej also, is not distinctly outlined. The inner margin is more so, by an elevated ridge or 

 ridges. Proximally its margin is partly formed by the nidimental costal, of a subcubic form attached by a suture in 

 a pit, as in T. suloatus. 



M. M. 



Length average vertebral, 0.035 



Width, greatest, .025 



" anterior, .0075 



" last vertebral, .010 



Length " " .017 



" Pygal, .081 



" united extremities two last costals. . ,03(i 



i 

 " penultimate costal, .104 



The vertebral regarded as of average form exhibits but a short lamina or neural spine connecting the arch and su- 

 perior plate. The neural arch is not coiissified with the centrum, and the capitular articular face is well developed. 



The inguinal articular pit is strongly marked and rather wide; distally its fundus is continuous with the plane of 

 the costal bearing it. 



M. M. 



Length inguinal pit, .032 



Width " " .000 



" costal bone bearing it, .0475 



" average costal bone, 0.33 



A marked character of the species is seen in the mesosternal bone, one-half of which is preserved. From the 

 acute angle formed by the extremity, it is evidently oven more transverse than that of T. molops. The sutures arc 

 very coarse, as in other species, the anterior directed forwards, the posterior outwards. The intergular scute is larger 

 than in the other speoies, as its right margin extends nearly to the outer and posterior sutures of the bone. All the 

 sutures of the plastron are coarse. 



The axillary margin of the byosternal is not thinned; that of the xiphisternal is thinned, and they enclose a wide 

 median emargination behind. Tlieir extremities are not so acute, as in one example of T. molops. The iliac scar is 

 very prominent and rugose;. The pubic scar is longer and much wider in proportion to the general size than in T 

 suloatus, and is wider behind than before. It is not elevated as in T. molops. Its sutural ridges are very numerous 

 and acute. 



M. M. 

 Length from median suture to xiphisternal posterior angle, ,059 



" xiphisternal scar, ,037 



Width " " (greatest), .0085 



The marginals are like those of T. molops, on a smaller scale. The posteriors are light, the anterior heavier 

 those of the bridge present a small angle, but not thin nor revolute. The reticulation is with their length. Length 

 and width of a, posterior marginal about equal, viz: m. 0.0468. 



The scapula is continued into a procoracoid with axis at right angles to it, and length of union not great, but 

 about as in Emydioid Pleurodira. 



M. 

 Diameter glenoid cavity. .014 



Length of sea.pnlo-procoracoid neck. .021 



