1895.] 4b5 [Cope. 



corresponding length in tlie quagga, while the parts are in other respects 

 as large as those of the domestic horse. The maxillary bone is produced 

 posteriorly to the last molar as far as in E. caballus. In E. occidentalis 

 this distance Is less. The last superior molar is larger than the penulti- 

 mate in E. intermedius ; it is equal or larger in E. caballus, while it is 

 smaller in E. occidentalis.* In the E. occidentalis figured by Leidy (Exct 

 Mamm. Dak. Nebr. PI. xxi), and in the one figured by me (Ann. Rept. 

 Geol. Surv. Tex. 1892), the palatine foramen is opposite the penultimate 

 molar. In the E. intermedius as in the E. caballus it is opposite the last 

 molar. In the symphysis the mental foramen is entirely anterior to its 

 posterior border, as in E. occidtntalis . This specimen belonged to a mare, 

 as it has no trace of canine tooth, the first time that I have observed this 

 character in an extinct North American horse. 



The Equus intermedius is then intermediate between the E. occidentalis 

 and the E. caballus. It agrees with the latter in its molars and palatine 

 foramen ; with the former in the occipital region, wide incisors and short 

 muzzle, and tends towards E. fraternus in the incisor cups. From E. 

 major it differs in the much less complex enamel folds. 



Measurements. mm. 



Length of last five superior molars 143 



" " true molars 86 



Diameters of p. m.iiS^"*^^«P°^^^"«^ ^^ 



( transverse 31 



Diamctersof m. i...S^°t«'"«P«st«"«^ 25 



( transverse 30 



Diameters of m. iii. . \ 'Anteroposterior 36 



( transverse 29 



Length of maxillary bone posterior to m. iii 40 



" " mandible from p. m. iii to external border of 



incisors 130 



Width at middle of symphysis above 34 



" ' ' base of I 3 63 



Transverse diameter of crown of I 2 21 



Anteroposterior diameter of crown of I 2 10 



Transverse diameter foramen magnum 14 



*' " occipital condyles 92 



Anteroposterior diameter occipital condj'les above 50 



SOPPLEMENTARY NOTE ON EqtJUS FRATERNUS LeIDY. 



Equus fraternus Leidy, Proceeds. PhiJa. Acad., 1858, p. 11 ; Postplio- 

 cene Fossils of S. Carolina, Tuomey and Holmes, 1859, p. 100, PI. xv 

 Figs. 6, 8, 16, 17, 18 ; PI. xvi. Figs. 23, 27-29. 

 This species is represented by a considerable number of teeth together 



♦ See Ann. Report Geolog. Survey of Texas, 1892, Plate xxii, Fig. 3. 



