HOLLAND AND PETERSON: OSTEOLOGY OF THE CHALICOTHEROIDEA. 247 
MEASUREMENTS OF SUPERIOR DENTITION. 
No. 2103 No. 10030 Y.M 
(Moropus elatus), (M. oregonensis type), 
mm. mm. 
Length of premolar-molar series.................-- 218 
P? antero-posterior diameter...................... 22 
ptiransverse diame ter aerey ere cele wenn eer 20 
P® antero-posterior diameter...............-.0005- 24 17 
IPsitransyverseqaiametenmeriny yi eee cer io oe 29 20 
P4 antero-posterior diameter...................... 26 18 
122 THINGS CHEMIN, oo56ao0db0ncccendcD4uaooo0E 30 23 
M! antero-posterior diameter.....................- 43 
NUStransverseiciametenven sre een on aia o 384 23 
M? antero-posterior diameter....................5. 56 
Mestransverserdiametehanmncereciae cee oa een 4]. 
M3 antero-posterior diameter................--+-+- 59 37 
Mestransverseidiameteranns saeeicieneaeeaniaae nee ce 42 33 
In comparing the measurements of Moropus with Macrotherium it is at once 
observed that the latter has much shorter and broader molar teeth. This also 
appears to be true of Chalicotherium goldfussi and of the Asiatic species, so far as 
the limited material permits of comparison. On the other hand it is of interest 
to note that in Schizotherium priscum and Nestoritherium pentelici the molars are 
longer than wide, in this respect more nearly approaching the American type. 
In Macrotherium grande the premolars show less complication in the details of 
structure, especially P’, the first in the series. It has the outline of the crown less 
triangular than in Moropus. Internally it is also somewhat less developed, forming 
an oblique longitudinal valley between the ectoloph and internal tubercle, instead 
of a basin as in the American species. 
The anterior external angle of the molars in Macrotherium is not developed 
as much as in Moropus, so that the tooth in the former genus is more quadrate in 
outline than in the latter; the molars are decidedly shorter, and the median fossa, 
which separates the anterior and posterior inner tubercles, is directed more ob- 
liquely inward and backward. Nevertheless the general configuration of the 
crowns is on the whole quite similar in the two forms. 
The I nferior Dentition. 
(Plate LIT.) 
Moropus elatus has three incisors on either side, which are somewhat like those 
in Equus. The lateral expansion of the crowns is, however, much less than in the 
