A NEW FOSSIL TURTLE, KINOSTERNON ARIZONENSKH, 
FROM ARIZONA. 
By Cuartes W. GILMORE, 
Associate Curator, Division of Paleontology, United States National Museum. 
INTRODUCTION. 
In a collection of vertebrate fossils made by Dr. J. W. Gidley in 
the spring of 1921, near Benson, Cochise County, Arizona, were two 
well-preserved turtle specimens, the first extinct representative of the 
family Kinosternidae to be found in North America. It is also of 
interest that they are the male and female of a new species about 
to be described. Both specimens were found in the same deposit 
of fossils, within a few feet of one another, and associated with a 
considerable fauna consisting of mammal and bird remains. 
Fight species of the genus Kinosternon are recognized in North 
America by Stejneger! and Barbour, of which only two, Kinosternon 
sonoriense LeConte and K. flavescens (Agassiz) are said to range into 
Arizona. It is the latter species to which the fossil form appears to 
be most nearly related. 
I wish at this time to express my appreciation of the assistance 
given me by Dr. Leonhard Stejneger of the United States National 
Museum, especially in the comparison of the fossil with the extant 
species of Kinosternidae, a work that was made comparatively easy 
because of his intimate knowledge of the living species. 
Family KINOSTERNIDAE.’ 
Nuchal plate produced into costiform processes, underlying the 
marginals. Plastral bones eight, the entoplastron being absent. 
Shell covered with epidermal shields. Caudal vertebrae procoelus. 
Neck completely retractile within the shell. Temporal region not 
roofed over; no parieto-squamosal arch. Digits moderately elongate ; 
phalanges with condyles; claws four or five. 
5X, TNR ONT IIS GTO ey ee NUN Pee PI ea 
1A check List of North American Amphibians and Reptiles, Harvard University Press, 1917, pp. 
111-112. 
2The definition of the family and genus is that given by Dr. G. A. Boulenger in his Catalogue of the 
Chelonians, Rhynocephalians, and Crocodiles in the British Museum (new ed.), 1889, p. 33. 
No. 2451|—PrRocEEDINGS U. S. NATIONAL Museum, VOL. 62, ART. 5. 
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