DERMATEMYDID^E. 28 1 



usually crosses on the proximal ends of" the third costals and the third neural starts, as usual, 

 on the third costals, but is carried forward so as to cross on the first neural. This sulcus in 

 the specimen is very distinct; besides this, it has been observed on another specimen. 

 In the median line, on the front of the first vertebral, is seen a distinct sulcus which runs back- 

 ward to the hinder border of the nuchal bone. Whether or not it extended further can not be 

 determined. Probably it attained to the transverse sulcus on the first neural. Apparently 

 the only explanation of this condition is to suppose that the first and second normal vertebrals 

 have coalesct; that the sulcus between the second and the third has been carried forward to 

 the first neural and even to the nucho-vertebral sulcus; thus dividing the united first and 

 second vertebrals into right and left halves. 



It seems probable that the third and the fourth vertebrals have coalesct; tor no sulcus 

 crosses the proximal ends of the fifth costals and the fifth neural. The vertebral occupying 

 the area of the fifth in other turtles has a length of 37 mm. and a width of about 30 mm. As 

 an individual peculiarity, the fourth costal scute of the left side is divided by a sulcus which 

 descends on the seventh costal bone. 



Fortunately the present specimen furnishes the epiplastra and the entoplastron, elements 

 not observed before (plate 43, fig. I ; text-fig. 353). The epiplastra are 37 mm. long; the width 



is 13.5 mm. at the middle of the length. They narrow ante- 

 riorly. The entoplastron is 19 mm. long, pointed in front, 14 

 mm. wide behind. These parts resemble considerably those 

 of Staurotypus salvinii (Boulenger's Chelonia, p. 31, fig. 10) 

 but the entoplastron is more pointed in the fossil species and 

 FIG. ^.-Anasteira ornata. Ante- the epiplastra are not so prolonged at their hinder outer 

 rior ends of three peripherals. an g' es - 



No. 6132 A. M. N. H. The whole length of the plastron is 86 mm. The bridges 



have a minimum width of 15 mm. It joins the peripherals 



x. sixth peripheral; v. seventh: z. eighth. < TI i i i j 



by coarse sutures. 1 he hyoplastron is only 4 mm. wide 



on the bridge. Its greatest fore-and-aft breadth is 1 1 mm. The fore-and-aft extent of the 

 hypoplastra is 21 mm.; that of the xiphiplastra, 27 mm. 



The bones of the plastron are markt by fine ridges and intervening grooves. On the 

 epiplastra these radiate from a point near the inner border, near the hinder end. On the 

 bridge the sculpture is transverse to the length of the body. 



Neither on this specimen nor on any others has the writer been able to find evidences of 

 epidermal scutes on the plastron. Doubtless these were present, but they were so delicate that 

 their boundaries have left no impressions on the bones. Dr. Baur could not find the sulci on 

 the plastron of specimens at Yale. 



Cope has mentioned the finding of specimens of this species on the "Upper Green River." 

 No. 1059 of the American Museum of Natural History bears his label to the effect that it was 

 found on Green River, at the mouth of the Sandy. The strata here belong to the lowest level, 

 A, of the Bridger. These have furnisht also Amyda aqua. Cope's specimen is somewhat 

 differently sculptured from the specimens from a higher level, the pustules predominating 

 over the ridges, on the peripherals. It is, however, probably not a distinct species. 



The evidence at hand shows that this species ranges from the lowest level of the Bridger 

 beds to the top of that known as C. 



Anosteira radulina Cope. 



Anostira radulina, COPE, Palaeont. Bull. No. 9, 1872, p. 555; Proc. Amer. Philos. Soc., xil, 1872, p. 555; 



Ann. Report U. S. Geol. Surv. Montana, etc., 1872 (1873), p. 620; Vert. Tert. Form. West, 1884, 



p. 128, plate xviii, figs. 18, 19. 



Anosteira radulata, BAUR, Ann. Mag. Nat. Hist. (6), III, 1889, p. 273. 

 Anostira radiolata, LYDEKKER, Cat. Foss. Kept., in, 1889, p. 144. 

 Anosteira radulina, HAY, Bibliog. and Cat. Foss. Vert. N. A., 1902, p. 447. 



This species was described by Cope from two peripheral bones, one from in front of the 

 bridge, the other from behind it. These are now in the U. S. National Museum and have the 

 number 4096. They were found in the Bridger Eocene near Ham's Fork, Wyoming, there- 

 fore in the lowest division, A, of the formation. The individual that furnisht these bones was 



