8 PROCEEDINGS OF THE NATIONAL MUSEUM, VOL. 62. 
Kinosternon arizonense apparently has its closest affinities with 
K. flavescens which now ranges into this same part of Arizona. It 
may be distinguished at once from that species by its much larger 
size; the more rounded anterior extension of the anal scutes, as 
contrasted with their longer and more pointed triangular shape in K. 
flavescens, which bring about a reduction of the femorals on the 
median line. Other differences might be pointed out such as the 
reduced number of neurals, broader anterior lobe, etc., but Doctor 
Stejneger, who has made an exhaustive study of the Kinosternidae, 
tells me that many of these features are so inconstant they cannot 
be relied upon for specific differentiation. 
EXPLANATION OF PLATES. 
PLATE 1, 
Carapace of Kinosternon arizonense. Cat. No. 10463, U.S.N.M. Type. Male. 
Superior view. About } natural size. 
PLATE 2. 
Plastron of Kinosternon arizonense. No. 10463, U.S.N.M. Type Male. Ven- 
tral view. About ? natural size. 
PLATE 3. 
Carapace of Kinosternon arizonense. No. 10462, U.S.N.M. Paratype. Female. 
Superior view. About natural size. 
PLATE 4. 
Plastron of Kinosternon arizonense. No. 10462, U.S.N.M. Paratype. Female. 
Ventral view. Natural size. 
Puate 5. 
Plastron of Kinosternon arizonense. No. 10462, U.S.N.M. Paratype. Superior 
view. Natural size. 
