E L. Troxell— Early Pliocene One-Toed Horse. 347 



boring outcrops. They are abundant in the Lower Pliocene 

 but in all probability soon became extinct. At this time they 

 seem to have reached their maximum size and are probably 

 best known by the spscimens, from Long Island, Kansas ; Teleo- 

 ceras fossiger (Cope) seems very close to the variety with short 

 stout limbs represented in the Oak Creek locality. 



Ivory from the main quarry, together with parts of tusks 

 and skeletal material from near-by places, shows the presence of 

 a very large proboscidian in the fauna. It may represent any 

 one of several types of Mastodon, which in the Early Pliocene 

 reached a very great size. 



An incomplete skeleton of Merycodus sp. was found an eighth 

 of a mile away and about seventy-five feet lower than the 

 stratum bearing the horse skeleton. This genus is well known 

 in the Miocene and Lower Pliocene and is rather common. 

 There is a general resemblance in all these forms except that 

 some are almost twice the size of others. The present speci- 

 men is one of the largest known to the writer and is, 

 therefore, assumed to be a very late form. It is more than a 

 third larger than the type of M. necatus sabulonis of Matthew 

 and Cook* and is twice the size of their smallest specimen : 

 Merycodus sp. indesc. ; it is also 1/7 larger than the type of 

 M. osborni (Matthew). Merriam reportsf Merycodus from 

 the California Pliocene or Late Miocene, and in size the speci- 

 men from the Tejon Hills is quite equal to that from South 

 Dakota. 



The absence of Merycodus in the Blanco of Texas is taken 

 as an evidence that the formation is distinctly more advanced 

 than most Pliocene deposits. Scott says " these peculiar 

 hypsodont deer persisted even in the Older Pleistocene," but 

 most authors do not credit them with such a long existence. 

 Osborn reports this animal mostly in the Lower Pliocene and 

 it seems quite probable that this was near the close of their 

 career. 



The single molar tooth of a grazing camel gives no trust- 

 worthy evidence as to the definite age of the formation, for 

 these camels are very abundant in the Llpper Miocene and con- 

 tinue on until the Pleistocene. 



In this single locality three-toed horses of the Protohippus 

 and Hipparion type were found, in addition to the new 

 species. Of the true Protohippus both large and small species 

 were represented. Three miles from the main quarry, an 

 almost complete specimen was found which resembles Proto- 

 hippus placidus, especially in its size. The association of feet 



* Matthew, W. D., Cook, H. J., Bull. Am. Mus. Nat. Hist., vol. xxvi, pp. 

 412, 1909. 



f Merriam, J. C, Univ. Cal. Publ., Bull. Dept. Geol., vol. viii, No. 13, 

 pp. 287, 1915. 



