+22 



FOSSIL TURTLES OF NORTH AMERICA. 



55 mm. thick. The posterior lobe is 173 mm. long to the apices of the xiphiplastra, and is 370 

 mm. wide at the base. The posterior notch is 1 10 mm. wide and 45 mm. deep. At the inguinal 

 notch the edge of this lobe forms a wall about 55 mm. high, having a rounded outer face and a 

 sloping inner face. Posteriori)' the wall diminishes rapidly in height, so that the thickness at 

 the xiphiplastral apices is only 30 mm. 



The entoplastron is rhombic in form, 156 mm. long in the midline, 195 mm. wide. The 

 hyoplastra meet along the midline for a distance of 176 mm., the hypoplastics 156 mm., and 

 the xiphiplastrals 145 mm. 



The nuchal scute is about 30 mm. long and wide. The marginal scutes rise to the sutures 

 between the peripherals and the costals. The supracaudal scute seems not to have been 



divided in the midline. It has a width along the free border of 

 200 mm. The vertebral scutes are very wide, especially those 

 behind the first. The table gives the dimensions. 



The gular scutes extend backward on the entoplastron. 

 The humerals have an extent of 100 mm. along the midline. 

 The pectorals are y^ mm. antero-posteriorly at the midline. 

 Beyond this they narrow for some distance, then expand greatly. 

 The abdominal scutes meet along the midline a distance of 

 207 mm.; the temorals, 100 mm.; the anals, 75 mm. 



The pelvis is preserved in position. It has a stout lateral 

 pubic process. The tubera ischii are conical, and their apices are 105 mm. apart. 



Testudo osborniana Hay. 

 Plates 72-75; text-figs. 552-562. 

 Testudo osborniana, Hay, Ann. N. Y. Acad. Sciences, xvi, 1905, p. ;i2. 



The type of the present species was secured in 1901, by Mr. Barnum Brown, near the line 

 between Colorado and Nebraska, north of Sterling, Colorado. The locality is in the latter 

 state. The deposits affording it belong to the Miocene, and are known as the Pawnee Creek 

 beds. The specimen belongs to the American Museum of Natural History, and bear its 

 catalog number 5868. It consists of a complete shell, the skull (lacking the lower jaw), the 

 pelvis, both hinder limbs nearly complete, and the tail. From the deeply concave plastron it 

 is concluded that the animal was a male. The total length of the carapace is 775 mm. 



The skull (figs. 552-554) is rather long and narrow for a Testudo, and the bones are moder- 

 ately thick and heavy. The sides of the skull are parallel from the squamosal processes to the 

 front of the orbits, beyond which they converge with nearly straight outlines to the rounded 

 snout. Seen from the side the upper outline of the skull is concave behind the orbits, above 

 and in front of them moderately convex. 



The following are some of the dimensions of the type skull : 



Millimeters. Millimeters. 



Snout to the end of the supraoccipital process. . 129 Width of interorbital space 26 



Snout to occipital condyle 119 Width of nasal opening transversely 26 



Width at the base of the quadrates . 8i Antero-posterior diameter of the orbit 29 



Width at the hinder end of the maxilla- 79 



The height of the skull from the cutting-edge of the maxilla to the upper surface of the 

 frontals is contained in the length from the snout to the condyle 2.8 times. 



The prefrontals meet along the midline a distance of 23 mm., and this is also the length of 

 the suture between the frontals. The orbits are subquadrilateral. The long axis, 30 mm., is 

 directed from the prefrontal border backward, outward, and downward. The jugal arch has a 

 width of 16 mm. The maxilla descends from the floor of the orbit a distance of 18 mm. 

 I he cutting-edge is concave, especially posteriorly, and is rather coarsely dentated. The 

 squamosal processes are not laterally comprest, but swollen, especially on the inner side; and 

 the outer, upper border rises but little above the upper surface of the paroccipital. 



The antero-posterior extent of the otic region, measuring across the paroccipital and 

 prootic, is 33 mm. and contained in the length of the skull to the occipital condyle 3.6 times. 



