Alen o 
Art. XLII.—Notice of new Tertiary Mammals. V: by 
Professor O, C. MARSH. 
much interest. All the specimens described are preserved in 
the Museum of Yale College. 
Hohippus validus, gen. et sp. nov. 
This genus is very nearly related to Orohippus, but may be 
readily distinguished from it by the dentition, the last premolar 
above and below being similar to the next premolar in front, 
their main features, are very similar, there being in each genus 
four well developed toes’ in front and three behind, but 
Fohippus has a rudiment of the outer, or fifth, metatarsal, and 
may have had a similar remnant of the first digit in the fore 
foot, The radius and ulna, and the tibia and fibula were 
distinct, and entire, and in most other respects the skeleton 
resembled that of Orohippus. 
he present species is based mainly upon a fragmentary 
skeleton, with the principal teeth well preserved. These 
Temains indicate an animal about as large as a fox, but of 
tather more robust proportions. Some of the more important 
measurements are as follows: 
Extent of three lower true molars Meee epee EN! ep Fore EE PATE Sead nca 
Tuto posterior diameter of last lower molar. --------- 112 
Ausverse diame eS es ee Bier en gat SNA ane 5°4 
putto-posterior diameter of last lower premolar ------- 7° 
A ere Giameter a ee 54 
Tt posterior diameter of first upper true molar - ---- v 
Pree Gameter ee 9°5 
bak he known remains of this species are from the Coryph 
th ».0T lowest Eocene. of New Mexico. This horizon is below 
at in which Orohippus occurs, 
