TRIONYCHID. 523 
are usually large, there being 2 in a line 10 mm. long; but on the distal ends there may be 3 
or 4 pits in this distance. These pits are arranged in somewhat irregular rows across the 
costal bones. Some of the ridges separating these rows are higher and have sharper summits 
than the others, these more conspicuous ridges running across the costals at a distance of 
about 10 mm. apart. There may thus be from 1 to 4 rows of pits between each two of these 
larger ridges. 
Amyda francisce sp. nov. 
Plates 102, 103; text-figs. 678, 679. 
The fine specimen to which the name dAmyda francisce is given was collected by Mr. 
Walter Granger, of the American Museum expedition of 1903, in the Bridger beds of Wyoming. 
The exact locality is the eastern part of the Grizzly Buttes; the level is that known as B. The 
specimen consists of the complete carapace and plastron; the seventh and eighth cervical 
vertebra; both scapule and both coracoids; the pelvis, mostly hidden by the xiphiplastrals; 
the proximal ends of both humeri; most of the right hind leg; the left femur; and most of 
the left hind foot. The catalog number of the type is 5936. 
Fics. 678 AnD 679.—Amyda francisce. ras 
678. Carapace. 
679. Plastron. ent, entoplastron; epr, epiplastron; /Ayo, hyoplastron; 
hypo, hypoplastron; «ph, xiphiplastron. 
In form the carapace (plate 102, text-fig. 678) is broadly elliptical, slightly truncated in 
front and more decidedly truncated behind. Antero-posteriorly the carapace is slightly archt; 
___ more strongly from side to side. The length in a straight line is 
leereateet 315 mm.; the greatest width is 293 mm. 
width. This species is referred to the genus 4myda because of the 
presence of 8 pairs of costals and the absence of a preneural. 
There are 7 neurals, of which the first is very large and the 
Neurals. Length. 
; A | ) 
2 Pa s | seventh much reduced. The anterior neural is considerably 
i 42 29 | broader in front than behind. The table herewith presents the 
ay Ba dimensions of the neurals. The four neurals succeeding the 
6 28 17 first are wider behind than in front; the next two are wider in 
7 27 7 front than behind. 
~ a The nuchal has a fore-and-aft extent of 36 mm., and is about 
130 mm. from side to side. The anterior border of the bone is occupied by a narrow, smooth 
band. There appears to have been a small median fontanel between the nuchal and the 
first neural. 
The form and the relative proportions of the costal plates may be seen from the illustrations. 
Their free borders are beveled off to an acute edge. The costal ribs are broad and they project 
