4 PROCEEDINGS OF THE NATIONAL MUSEUM. VOL. 62. 
were separated by the intervention of the first costals meeting on the 
median line as in Kinosternon leucostomum as figured by Boulenger.? 
In the type there are six neurals, all except the sixth being present. 
That a reduced sixth neural existed is clearly indicated by the exca- 
vated ends of the sixth pair of costals which unite on the median line 
posterior to the sixth neural, as shown in Figure 1. All except the 
sixth are longer than wide. 
Measurements of neurals in millimeters. 
Length. | Width. 
No. 
Type. Paratype. Type. Paratype. 
Mo eegar sede oeeeondes Dao boc odo Ges cHOUOOE.G 17.5 12.5 9 5. 5 
Do oe HNO Hance bate: ot Pole oe A REN cee a eran TS Oy lbs he eee eke 13 10 
ae eee Se Ei. aA 18 19 13 | 11 
CP SS oto R eer, Ces /caeis CRONE EER He RISER eS ak been 14.5 17 13, | 9.5 
BBA Sgek c acathe wine bree iata eure ata Seater acaraye LOM NA aa eee ee LOE aes 
CO A se MES os FS See SEER TS Si) EEE Breeylat ceeetetes OF) 26 wheres 
There are the usual eight costals of which the sixth, seventh, and 
eighth pairs meet on the median line. The single suprapygal in the 
Fig. 3. CARAPACE OF KINOSTERNON ARIZONENSE. NO. 10463, U.S.N.M. TYPE. 
MALE. VIEWED FROM THE LEFT SIDE. ONE-HALF NATURAL SIZE. 
type is large, having a greatest transverse diameter of 41 millimeters. 
The pygal is 26 millimeters wide and 18 millimeters long. 
There are ten pairs of peripherals. The second in the type meas- 
nres 22 millimeters from the free border to the union with the first cos- 
tal plate; the fourth 20 millimeters; the seventh 24 millimeters; and the 
tenth 25.5 millimeters. The peripherals of the paratype, except for 
their smaller size, are identical in other respects. The fifth and sixth 
unite firmly by suture with the plastral bones as shown in Figure 7. 
The paratype shows the nuchal scute to be very small. The ver- 
tebrals in both specimens are wider than long, being widely and 
acutely expanded at their centers. 
3Catalogue of the Chelonians, Rhynocephalians, and Crocodiles in the British Museum, 1889, fig. 12, 
pp. 35. 
