. Carnegie Institution of Washington publication. 234 FOSSIL TURTLES OF NORTH AMKRICA. beds of the same period in the region about Milk River, British America. As the Judith River beds are now known to be much lower in the geological scale than the Laramie it is probable that a distinct species is there included. The Arapahoe and Denver beds being prob- ably above the Laramie, it is not improbable that the remains reported from that horizon bv Cope and Marsh belong to a third species of the genus. Leidy's type indicated a turtle whose carapace had a length of about 365 mm. The neural, regarded
. Carnegie Institution of Washington publication. 234 FOSSIL TURTLES OF NORTH AMKRICA. beds of the same period in the region about Milk River, British America. As the Judith River beds are now known to be much lower in the geological scale than the Laramie it is probable that a distinct species is there included. The Arapahoe and Denver beds being prob- ably above the Laramie, it is not improbable that the remains reported from that horizon bv Cope and Marsh belong to a third species of the genus. Leidy's type indicated a turtle whose carapace had a length of about 365 mm. The neural, regarded as the fourth, was 26 mm. long and 27 mm. wide. The costal plate believed to be the fifth, was 28 mm. wide at the middle of the length. It is rather strongly archt, showing that the shell was not deprest. This costal had a thickness of 7 mm. where it joined the neurals. It is crost at the proximal end by the costo-vertebral sulcus, from which proceeds the sulcus that separated the third and fourth vertebral scutes. The position of the longitudinal sulcus indicates that the vertebrals had a width of about 65 mm. Leidy's estimate that they were 2 inches wide is too small. The specimens figured by Cope in his Vertebrata of the Cretaceous Formations of the West, plate vi, figs. 15, 16, were collected in 1873, in northeastern Colorado. No statement is made as to the exact locality, but they probably came from the Denver beds in the region about Bijou Creek. We can not be really certain that they belong to Leidy's species. Cope's fig. 16 represents a posterior peripheral, apparently the ninth of the left side, with the sulcus between the third and fourth costals running down its anterior half. The bone is 39 mm. high, 32 mm. wide at the free border, and 9 mm. thick at the costal border. There is no pit for the rib-end. The bone thins to an acute free border. The upper surface is only slightly concave. The sculpture resembles that of the type of the species. A remarkable feature of t
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