242 FOSSIL TURTLES OF NORTH AMERICA. 
the hyoplastron in front of the axillary notch is acute, differing thus from 4. agilis and 4. 
beatus. The hyoplastral and the hypoplastral portions of the median suture are nearly equal 
in extent; whereas in 4. agil1s the hypoplastral portion is considerably longer than the hyo- 
plastral part. The transverse suture between the anterior and posterior halves of the plastron 
is very coarse, there being alternately large pits and processes for mutual gomphosial articu- 
lation. The form and proportions of ee hinder lobe may be determined from the table on 
this page and from the figure. The free borders are acute, with a parallel groove on the upper 
surface. The scar for the pubis resembles that of the other species, but it is more deeply 
imprest. Just in front of the hinder border of the xiphiplastrals and lying across the midline 
there is a conspicuous elevation, the thickness of the bone here being 16 mm. In the center 
of the lobe the bone thins down to about 10 mm. 
The pectoral scutes are of considerably greater extent antero-posteriorly than in 4. agilis, 
68 mm. as opposed to 36 mm., the humero-pectoral sulcus swinging well forward on the ento- 
plastron. The abdominal scutes are larger than those of any of the five species compared 
with this one in the table, the sulcus between them being 135 mm. long. The femoral scutes 
also exceed those of the other related species, being 100 mm. in the midline. The anal scutes 
are relatively short, 75 mm. ‘There are 3 inframarginal scutes on the bridge, the middle one 
Table of measurements of species of Adocus. 
A. beatus. A.agtlis. | A. syntheticus.| A. punctatus. A. lacer. A. pravus. 
Length of plastron. : 420+ sye¥e 454 356 sete 450+ 
From hinder enh ‘of ento- 
plastron to rear of plastron 340+ 310 346 283 355 ere 
Hyoplastron on midline...... 100+ 95 R. 85 80 125 110 
L. 115 
Width of bridge............ 160 185 200+ 144 192 
Hypoplastron on “araline 11S 120 R. 147 105 120 130 
L. 120 
Length of hinder lobe... ..... 148 130 145 130 140 
Length of xiphiplastron...... 120 100 115 100 115 
Width of plastron at bridge... Ane 290 380 280 285 fey 
Width of anterior lobe at base 160 210+ Sats 190 oer 180 
Width of hinder lobe at base. . 175 177 230 176 177 BS 
Width of entoplastron....... 88 91 95 ay 88 70 
Length of entoplastron. . : 54 69.5 
Thickness at crossing of asd: 
MAN SUCUEES «6 6 coca cee neais 14 1a 16 Ae 17 12 
Thickness of epiplastron at 
SYMPNYSIS. cass eos. ae etn 15 Pees 14 
Thickness of hyoplastron in 
front of axillary notch..... 1S 14 14 ate 14 
Thickness at front of xiphi- 
plastron in midline........ 17 16 18 36 3 
being 107 mm. long and 28 mm. wide. In the aauge the sulci are especie as being prema: 
than they really are. 
The plastron is considerably eroded. The lower surface is furnisht with numerous small 
pits, some of them resembling pin-holes, but to what extent these are due to weathering it is 
difficult to say. 
The anterior rim of the carapace, from one axillary notch to the other, shows that at 
these notches the carapace had a width of 455 mm. Whether or not the carapace expanded 
backward, as it does in 4. punctatus, can not now be decided. The front (plate 34, fig. 8) 
is almost exactly an are of a circle whose radius is 197 mm. The front of 4. punctatus is 
somewhat truncated. The rim is thick and heavy, except that the nuchal bone is excavated 
on its hinder surface, so that its thickness is only 14 mm. At its articulation with the first 
peripherals it has increased to 25 mm. The greatest thickness of the third peripheral, just 
in front of the axillary notch, is 40 mm. 
The upper surface of the nuchal and of the anterior peripherals is slightly convex from 
above downward. ‘The free edge is rather thin and is somewhat reverted, as in 4. punctatus. 
The lower side of the peripherals is very convex from front to back; that of the nuchal con- 
cave. The free border of the nuchal measures 75 mm. At its upper, or hinder, border it 
