CHELONIID^. 211 



The writer has been permitted to examine these specimens thru the courtesy of the 

 present state geologist, Prof. William S. Yeates. 



In the American Museum of Natural History is a small collection of bones, without indi- 

 cation of origin, but which are provisionally assigned to the present species. The number of 

 the lot is 1410. They are a part of the Cope collection and evidently were found in New Jersey. 

 These bones are filled with iron pyrites and they are black, with some surface stain of chocolate. 

 One fragment is that of a costal. The sutural border is 12 mm. thick, but thru the rib 

 the thickness is 17 mm. The upper surface is covered with coarse ridges and tubercles, irregular 

 in size and arrangement. They resemble greatly those of Amyda virginiana illustrated on 

 plate 96, figs. 7, 8. Another fragment appears to be the upper end of a costal, with the base 

 of the rib-head. The thickness varies from 7 mm. to 10 mm. The fragment is 75 mm. wide. 

 Another piece seems to be a part of a peripheral, showing the acute free border, but not extend- 

 ing to the costal border. The length of the fragment is 56 mm.; the width, 63 mm.; the thick- 

 ness of the upper border, 21 mm. The upper surface is convex from the free border upward, 

 while the lower surface is concave. One end appears to have come close to the suture, and 

 here the tubercles run at right angles with the suture. Those at the outer end are small and less 

 elongated. Between the two regions are some ridges running at right angles with the free border. 



Three fragments belong to the plastron. The best of these resembles the outer end of the 

 left hyoplastron of the loggerhead. The fragment is 135 mm. long, 67 mm. wide, and 2O mm. 

 thick at the proximal end. Toward the outer end the bone thins and ends in a number of 

 digitations. The border, supposed to be axillary, is concave in outline, with the edge obtuse 

 near the digitations, but subacute more proximally. The supposed hinder border evidently 

 articulated with another bone, probably the hypoplastron, out nearly to the digitated border, 

 thus abolishing the fontanel. The greater part of the inferior surface of the bone is orna- 

 mented with anastamosing ridges and some tubercles, about three or four of them lying along 

 a line 20 mm. long. 



Genus SYLLOMUS Cope. 



Costal bones suturally articulated with the peripherals. Surface of carapace sculptured 

 with grooves and ridges. Humerus much flattened distally. Ectepicondylar passage a com- 

 plete foramen. Radial process remote from head of bone. 



Type: Syllomus cnspatus Cope. 



Syllomus crispatus Cope. 

 Plate 32, 6gs. I, 2; teit-fig. 169. 

 Syllomus crispatus, COPE, Proc. Amer. Philos. Soc., xxxv, 1896, p. 139. HAY, Bibliog. and Cat. Foss. 



Vert. N. A., 1902, p. 442. 



The remains on which this species was based are now in the American Museum of Natural 

 History and bear the number 6134. These remains consist of the right humerus, lacking only 

 the ulnar process, and 2 fragments of costals. These were collected by Cope in Miocene 

 deposits, on the Pamunkey River, Virginia. 



The first fragment of costal belongs to the distal end of the bone (plate 32, fig. i). The 

 width at the end is 47 mm., but this diminishes proximally. The thickness at the proximal 

 end of the fragment is 6 mm.; but at the distal end this has become only 2 mm. This border 

 articulated by close suture with the contiguous peripheral. Doubtless the rib passed beyond 

 the border and entered a pit in the peripheral. The surface of the bone is sculptured with 

 anastomosing grooves and ridges, usually parallel with the long axis of the costal. The sculp- 

 ture becomes coarser toward the proximal end of the bone. Parallel with and close to the 

 peripheral border is a shallow groove which may be a portion of a costo-peripheral sulcus. 



The other fragment of costal comes from near the neural end (plate 32, fig. 2) and the 

 width is 45 mm. It is crost by a narrow, but sharp, ridge, which indicates that the carapace 

 was traverst on each side by a lateral keel. We may also safely assume that there was a median 

 keel. The thickness of the bone, on what is probably the proximal side of the keel, is 7 mm. 

 Toward the distal end the thickness diminishes. The surface of this fragment is more coarsely 

 and irregularly sculptured than that of the other and the elevations vary more in size and form. 

 No trace of sulci appears on this fragment. A portion of the surface is, however, destroyed. 



