EMYDIDZ. 319 
the costal plates are alternately wide and narrower at their opposite ends, the beveled surface 
of the upper side of the hinder lobe is narrower and the axillary scute is far from reaching the 
fifth marginal. Other differences are noted under FE. oc yrrhoe. E. arethusa is distinguisht 
by the contracted epiplastral lip and other characters. 
E. stevensoniana is distinguisht from £. septaria, which it most resembles, by not having 
the anterior lobe so much expanded, and by not having the costo-marginal sulcus so near the 
upper edge of the peripheral bones. The form and rhe dimensions of the anterior marginal 
scutes are quite different in the two species; and the pectoro-abdominal sulcus of E. steven- 
soniana does not approach so closely at the midline the hyohypoplastral suture as it does in 
both the specimens of FE. septarra in the American Museum. 
Echmatemys septaria (Cope). 
Text-figs. 414-420. 
Emys septarta, Cope, 6th Ann, Report U.S S. Geol. Sury. Verrs., 1873, p. 625; Amer. Naturalist, xv1, 1882, 
p. 992; Vert. Tert. Form. West, 1884, pp. 130, 139, plate xvi, hgs. g-13.—Hay, Bibliog. and Cat. 
Foss. Vert. N. A., 1902, p. 448. 
Echmatemys septaria, Hay, Bull. Amer. Mus. Nat. Hist., xxi, p. 28, fg. 1. 
The type of this species is in the U. S. National Museum and consists of a tolerably com- 
plete plastron; a portion of the central region of the carapace, including the third, fourth, and 
fifth neurals, with portions of the second, se and fourth left costals; and a fragment showing 
parts of the fifth, sixth, and seventh night costals and abutting peripherals. ahve type was 
collected in the beds of the Washakie basin in the badlands of South Bitter Creek, W yoming. 
All of Protessor Cope’ s illustrations are one-third the natural size, instead of one- fouethi: 
Fig. 12 represents the piece w hich includes the three neurals mentioned and the corresponding 
couenle: but the sutures bounding these bones are not shown. Moreover, the lower end of the 
figure is the forward end of the fragment. The fragment illustrated by fig. 13 is not pee to 
have had any connection with that of fg. 12; but che two pieces join accurately. If fig. 13 
conceived as being swung around so that the end of the suture near its lower right- hand < corner 
shall coincide with the end of the fracture seen in fig. 12, at the bottom of the concave 
border on the right-hand side, the pieces will be in their natural relation. 
The frst neural bone is 42 mm. long and 23 mm. wide. The next two neurals, all whose 
form can be determined, are hexagonal, with the broad end forward. Of these the second is 
35 mm. long and 30 mm. wide, w hile the third is 40 mm. long and 27 mm. wide. The periph- 
erals are high, che fourth and fifth rising above the edge of the shell about 42 mm. The 
nuchal and che peripherals abutting on it have sharp free borders: The nuchal is 50 mm. long 
and 67 mm. wide. 
The first vertebral scute is 67 mm. long and 80 mm. wide; the second 78 mm. long and 
66 mm. wide at the point of he, brackets. The nuchal scute is narrow, abet 20 mm. All 
the epidermal sulci are rather deeply imprest, but are not broad. 
The inguinal buttresses extend well up into the carapace. They reach inward about 
40 mm. fon the inner surface of the fifth costal plate. They are very thin in comparison with 
those of E. shaughnesstana. Cope states (Ann. Rep. Hay den Sury. for 1872, P- 625) that this 
buttress is connected with both the fifth and sixth costal plates. An examination of his type 
shows that on the left side the union is almost entirely with the fifth costal, while the sixth only 
just comes into contact with the buttress. On the right side the sixth takes more part in the 
articulation. The position of this buttress probably varies somewhat in different individuals 
of this species. In No. 6085, American Museum of Natural History, described below, it 
comes into contact with the sixth costal. In No. 1077, American Museum of Natural His- 
tory, the buttress rests on the middle of the fifth costal (fig. 414), and is hence far from the 
border of the sixth; but this specimen appears to be abnormal in some other respects. “There 
are considerable differences between Cope’s type and No. 1077 in the structure of the costals 
and peripherals in the region of the inguinal notch. There is ae considerable difference in the 
widths of the costals, | the peripherals coincide pretty closely with the ends of the costals. 
In No. 1077, American Museum of Natural History, the arrangement is as shown in fig. 414. 
This figure shows parts of the fourth, fifth, sixth, and seventh costals and the seventh, eighth, 
