AND AVES OF NORTH AMERICA. 



16G-A 



an anterior rib. The axilliary pit is less prominently margined by a high osseous wall, and it is elongate and curved 

 forwards, nearly reaching the margin of the bone. The rib head is complete. 



With its fellow, it embraces a first vertebral, which is about twice as long as wide and six-sided. The sides an; 

 in the order of their length: posterior (shortest), anterior, postero-lateral, antero-lateral. The anterior marginal is 

 narrow in front. It expands so much posteriorly as to make the first lateral almost triangular. The second marginal 

 is nearly quadrate. The edge of these marginals is thin above the nape, and thickens laterally. In the posterior it is 

 gradually thinned out and a very little recurved. The second vertebral bone is not so long as broad: those following 

 increase gradually in length. 



The narrow extent of the hyposternal bono in front of the inguinal crest indicates as in T. molops, an intermar- 

 ginal sternal. The sutures retires posteriorly from that point, suggesting the continuation of that bone towards the 

 middle lino. The cavity of the plastron is extended well laterally at the bridge. The hypo-xiphisternal suture is 

 nearly transverse. The pubic scar is little elevated, and broadest posteriorly. Its median crest extends throughout, 

 the whole length. The posterior margin of the xiphisternal is not preserved. The mesosternum is of a rounded form, 

 but obtusely pointed behind, and with lateral rounded projections. The posterior sutures arc bevelled forwards and 

 upwards. 



The sculpture is much like that of Taphrosphys sulcatus. The marginal bones have a, delicate transverse reticula- 

 tion, and the costals a coarser longitudinal one. The under surfaces do not present any sculpture, perhaps, on account 

 of corrosive action. 



M. 

 Length of last costal, .08 



iliac pit, .03 



" pubic scar, .024 



" third costal bone, .10(5 



Width third (costal bone proximally), .0343 



(distally), .020 



(proximally), .007 



(distally), .0035 



(greatest), .001 



.089 

 -0182 

 .09 

 ..03 



Thickness " " 



a n u 



Width first 

 Length " vertebral, 

 Width " " 



" second " 

 Length " " 



Length median marginal, 

 Width " 



" hyposternal, 

 Thickness " 

 Length ' ' 



" niesosternal, 

 Width 



-.008 

 (anterior), .0337 



(posterior), .003 



.063 

 ..004 

 -093 

 .0805 

 .0315 



The dermal scuta have been thin, as in other species of this group. The sutures arc all straight except that be- 

 tween the first and second vertebrals, which is convex backwards. The vertebrals are broader than long, and their 

 external angle; is near the middle of the length of the costal bones. The anterior vertebral is of longer form than the 

 others, somewhat like the frustrum of a triangle, of which the base is anterior. The second marginal is wider than 

 long; the third longer than wide. The intergular scutum is subtrigoual, the apex shortened by short facets, and ex- 

 tending three-fourths the distance to the posterior margin of the bone. 



This species was discovered by my friend, Dr. Samuel Lockwood, who lent the single 

 and typical specimen from his private collection for description. It is dedicated to Prof. 

 J. P. Lesley, the Geologist, and Secretary of the American Philosophical Society. 



