496 PROCEEDINGS OF THE NATIONAL MUSEUM VOL. 92 
Platygonus is now known to occur in several upper Pliocene depos- 
its, including those at Blanco, Texas; Hagerman, Idaho; Coso Moun- 
tain, Calif.; Eden?, Calif.; Meade County, Kans.; and Safford, Ariz., 
as well as Benson. In those cases where the symphyseal portion 
of the lower jaw is known at this stage, the third lower incisor is 
persistent as indicated in the Hagerman and Coso Mountain material. 
Camelid sp. 
Camelids are represented in the Benson collection by portions of 
the maxillae of one individual, no. 12856, including M’* to M$ of the 
right side and part of P*, M‘, and the posterior alveolus for P* on 
the left side. A few isolated foot bones were added to the collection 
in 1936, 
The presence or absence of P? cannot be determined, but it may be 
supposed that at this stage the tooth was absent, as it appears to have 
been in JMegatylopus, Camelops, and the several other forms which 
have been named from upper Pliocene and Pleistocene horizons. 
The teeth in the maxillae are much worn, so that only a small frac- 
tion of an inch remains to the depth of the crown of M’, and perhaps 
slightly more than an inch of the rather poorly preserved M*. Because 
of this, comparisons with material and figures of the various described 
forms are difficult; however, even at this advanced stage of wear teeth 
of relatively large size are indicated, having considerable occlusal 
area. 
The form may not have been appreciably larger than some of the 
material which has been referred to species of Camelops. ‘There 
appears to be noticeable variation in the size of the teeth in speci- 
mens from Hay Springs, Nebr., referred to Camelops kansanus, and 
also in material from American Falls, Idaho, referred to Camelops 
hesternus. I doubt if this represents more than individual variation 
in each case. The Benson teeth compare favorably in size with cer- 
tain of the larger teeth from these localities, but are noticeably greater 
than the average. 
Comparison with Megatylopus? spatula (Cope) ** from the Blanco 
formation is not satisfactory inasmuch as the only described material 
is the type lower jaw. The measurements given by Cope for the lower 
teeth do not indicate an animal significantly greater in size than the 
Benson camelid. Matthew and Stirton™ regarded the Blanco form 
as representing Paracamelus, a genus of large camels described by 
Schlosser 1° from the Pliocene of China. J. T. Gregory *’ in review- 
144. D. Cope, 4th Ann. Rept. Geol. Surv. Texas, for 1892, pp. 70-78, pl. 21, figs. 1-2, 1893. 
15 WW. D. Matthew and R. A. Stirton, Univ. California Publ. Bull. Dept. Geol. Sci., vol. 
19, No. 17, p. 367, 1930. 
16Max Schlosser, Abh. bayer. Akad. Wiss., math.-phys. Kl., vol. 22, p. 95, 1903. 
177, T. Gregory, Proc. Geol. Soc. Amer., 1936, p. 388, 1937. 
