PLEUROSTERNIDJE. 53 



The first costal (plate 7, fig. I; text-fig. 28) has a length, from its union with the neural 

 to the pointed distal end, of 103 mm. and a width, fore and aft, of 50 mm. The thickness of 

 the costal at the posterior border is about 5 mm. The anterior half of the bone is thickened 

 to as much as 18 mm. to form a shoulder for the reception of the axillary buttress of the plastron. 

 The latter must have been considerably more strongly developt than in Glyptops plicatulus. 

 The head of the rib is stout. The first rib lies in front of and against the rib of the first costal 

 plate. The first peripheral lacks its anterior half so that its antero-posterior extent can not be 

 accurately determined. However, the missing portion is partlv supplied by No. 1939. The 

 anterior, or free, border is obtuse. At one end is the sutural surface tor union with the nuchal 

 bone. It appears quite unlikely that there was any considerable excavation in the front of the 

 carapace for the neck of the animal. The first peripheral of No. 1930 was 30 mm. wide, 

 parallel with the edge of the shell. The second peripheral has a fore-and-aft extent of 40 mm. 

 and the width along the free border is the same. This border also is obtuse (fig. 29) and at a 

 short distance from the edge the thickness is about 8 mm. It resembles very closely the 

 corresponding one in G. plicatulus. 



The posterior peripheral, probably the tenth of the right side, numbered 1939, is 39 mm. 

 wide from the free border to the union with the costal, and 35 mm. along the free border. 

 Its thickness, where it joined the costal, is 10 mm., and it has come down to an acute free 

 edge (fig. 30). Its form is therefore that of a thin wedge. 



The fragment of costal numbered 1930 (plate 7, fig. 2; text-fig. 31) shows neither the 

 length nor the breadth. The piece is 35 mm. wide and has an epidermal sulcus running 

 parallel with the sutural border and 27 mm. distant from it. The costal was therefore of 

 considerable total width. Its thickness is only 5 mm. The true rib does not appear on the 

 lower surface, as it does in G. plicatulus. 



The sulci of this species are narrow and shallow, but quite distinct. Apparently the 

 epidermal scutes resembled those of G. plicatulus, altho neither the vertebrals nor the marginals 

 were so broad as in the latter species. 



The sculpture of the surface is quite different from that of G. plicatulus. In the latter it 

 has a more granular appearance and is produced by distinct raised dots and by short ridges 

 formed of coalesct dots. In G. ccelatus the dots are larger, the ridges also broader, longer, and 

 smoother. The spaces between the elevations are as wide as the latter. In the centers of the 

 bony surfaces the ridges are irregular in length and direction, and often vermiculate. Border- 

 ing the sutural edge is a broad band in which the ridges and grooves run at right angles with 

 the suture. On the costals this band may be as much as 13 mm. wide. 



Glyptops? belviderensis (Cragin). 

 Plate 7, figs. 4, 5. 



Plesiochelys belviderensis, Cragin, Colorado Coll. Studies, v, 1894, p. 71, pi. ii, figs. 1-8. Hay, 

 Bibliog. and Cat. Foss. Vert. N. A., 1902, p. 439. 



The present writer has not seen the type specimens of this species. They belong to Colo- 

 rado College, Colorado Springs, Colorado. They consist of two first costals, fragments of other 

 costals, a neural bone and a dorsal vertebral centrum. These bones were found in the Kiowa 

 shales, a portion of the Comanche series and near the top of the Lower Cretaceous. The 

 locality is near Belvidere, Kiowa County, Kansas. 



Dr. Cragin referred these bones to the genus Plesiochelys, but there appears to be no special 

 reason for this assignment. The species of this genus, so far as certainly known, belong to the 

 Jurassic, Kimeridge, and Wealden of Europe. The sculpture of the costals of Cragin 's species 

 suggests Glyptops ccelatus and accordingly the species is referred with doubt to Glyptops. Two 

 of Cragin 's figures are here reproduced. Fig. 5, plate 7, represents a neural seen from the 

 under side. It is relativelvconsiderablv broader than theneuralsof Plcsioc helys (Zittel 's Hand- 

 buch Palaeontologie, p. 545, fig. 502; Lydekker's Cat. Foss. Rept., pt. in, fig. 44). The front 

 costals figured by Cragin are narrow, the width being 38 mm., the length 82 mm. The longest 

 costal was 1 1 1 mm. long. The upper surface of the shell is said to be ornamented with deli- 

 cate vermicular grooving and pitting. Fig. 4, plate 7, is intended to represent this sculpture 

 of the costals. 



