1883.] Geology and Paleontology. 407 
Postglenoid process present; posttympanic and paroccipital not 
distinct. All the vertebre with plane articulations. Humeral 
condyles without intertrochlear ridge. Femur with third trochan- 
ter. Digits of posterior foot probably five. Metapodial keels 
small and posterior. 
Of this family Pantolambda is as yet the only known genus. 
Its leading cranial characters are as follows: 
anine teeth large; dental series continuous. Superior mo- 
lars all triangular, that is with a single internal cusp. External 
cusps of premolars unknown; of molars two. Internal cusp V- 
shaped, sending its horns externally as cingula to the anterior 
and posterior bases of the external side of the crown, without in- 
termediate tubercles, Inferior true molars with a crown of two 
Vs, the anterior the more elevated. Premolars consisting of one 
open V, with a short creston a short heel, as in Coryphodon. Den- 
tal formula I'3; C.1; P-m. 2%; M: 3; the last inferior with a heel. 
A strong sagittal crest. Auricular meatus widely open below. 
Large postparietal, postsquamosal and mastoid foramina. 
The brain case indicates small and nearly smooth hemispheres, 
extending with little contraction into a rather large cerebellum. 
The olfactory lobes are produced anteriorly at the extremity of 
a rather long isthmus. 
If we consider the dentition alone, Pantolambda is the an- 
cestor of Coryphodon. The history of the feet requires further 
elucidation. , 
The Pantolambda bathmodon is about as large as a sheep, and 
comes from the upper beds of the Puerco.——E. D. Cope. 
NOTE ON THE TRITUBERCULATE TYPE OF SUPERIOR MOLAR AND 
THE ORIGIN OF THE QUADRITUBERCULATE.—It is now apparent that 
the type of superior molar tooth which predominated during 
the Puerco epoch was triangular or tritubercular; that is, with 
two external, and one internal tubercules. Thus of forty-one 
Species of Mammalia of which the superior molars are known, 
all but four have three tubercles of the crown, and of the remain- 
ing thirty-eight all are triangular excepting those of three species 
t Periptychus, which have a small supplementary lobe on eac 
w of the median principal inner tubercle. 
_This fact is important as indicating the mode of development 
of the various types of superior molar teeth, on which we have 
not heretofore had clear light. In the first place, this type of 
noar exists to-day only in the insectivorous and carnivorous 
C arsupialia ; in the Insectivora, and the tubercular molars of suc 
Maka lig as possess them (excepting the plantigrades). In the 
c gulates its persistence is to be found in the molars of the 
E oo of the Wasatch, and Dinocerata ol the iy 
Superior n later e it is chiefly seen only in 
superior mola pochs it i iefly y 
10r molar, i s 
= It is also evident that the quadritubercular molar is derived 
‘ 
