Page 15 - maxson1928

IZ.

Comparative :'.easu.rements

1,I. californicus L califor .. icus 1.:. sumani

(Mint Canyon,No.18) {type M:~, No.21246) ltype, No.21422)

Antero-posterior
dia.'Tieter 18.1 ------------ 17.7 ----------- 19.7

riransverse " 15.0 15.2 ------ ----- 15.5
1
Height 31.0 29.5 --------- 32.8

I.:. isonesus from the 1.:ascall is less advanced than the :,:int

Canyon form. TL sumani from the :8arstow has a protocone tending to

become circular, a heavier coat of cement, and the tooth as a whole tends

to be somewhat larger. Vii th r.c. californicus the r:int Canyon specimen shows

close agreement and is therefore referred to that species.

L!ERYCHIPPUS INTERMONTANUS :Merriam

A much worn upper premolar two (No. 30042, Univ. Calif. Coll.), a

fragmentary upper premolar four,.and well worn lower premolars two and

three (No. 30041, Univ. Calif.) a.re referred to this species. Some incisors

(No. 30043, U.C.) and a canine (No. 30044, U.C.) from the same locality

(No. 3555 U.C. Coll. Loe.) are apparently also to be referred to the same

form. Plate I. Figures 2-5.

p§ shows a rather light coating of cement but this may not be a
general feature.for the lower teeth considered ~s pertaining to the species

are heavily cemented. 'l'he fossettes open into one another and communicate

with the outside through a valley between the protocone and hypocone.

The fossette borders are simple. This type of pattern has been produced

in several merychippine forms and several protohippine forms. :.'.erychippus

sejunctus (Cope) from the Pawnee Creek formation of northeastern Colorado

and Protohippus perditus (Leidy) from the Niobrara River formation of