Cope.] g 222 [Dec. 21, 
The external crescents of the true molars present prominent anterior an- - 
gles, which form strong vertical ribs. The first superior premolar has a 
weak, and the second premolar a very strong internal basal cingulum ; there 
are no other cingula. The diastema is as wide as the diameter of the canine. 
The first inferior premolar is one-rooted, and the second two-rooted, and 
both are longer than wide in horizontal diameter. The middle pairs of in- 
cisors are very small; the external one on each side is much larger, the 
diameter equaling half that of the canines. The first and second true mo- 
lars are subequal, and are together longer than the third, which does not 
quite equal in length the three premolars. The heel of the last molar is 
not so long anteroposteriorly as each of the othercolumns. Thesymphysis 
is steep, but is everted at the incisive region. 
Measurements. 7 M. 
Length of ramus from heel of m. III.................. 065 
sf OLMOAL SEPIES a. cissageea ad eu ai arernane avele nee cacseard Gmshace 036 
eS Of PLEMOlar SETIESs 6sisie is asia aes saree sieeinie eons 016 
a Of SeCONG CRUG AMOLARs cpio: ada dee cicsice’s o's viecvionn O11 
Widthof “ a lS wiegteg Es vinues dy ealyeae ee 006 
Length of third i SE De ctla ate antiea islig cae trenchant 016 
Widtivot “Ae TONS, cay sumeson nie oe Ga eee 006 
Length of symphysis in front.............. 5 detvaroivanaltie 025 
Depth of ramus at first premolar.............- ef isis 022 
o us Second true Molar... sc0c2. cee vaveed ss 025 
Width between superior anterior premolars........... . .014 
CYCLOPIDIUS HETERODON sp. nov. 
This species is represented by a portion of the right maxillary bone, 
which supports the last premolar, first true molar, and portions of other 
teeth. It is a smaller form than the B. simus, and differs in several import- 
ant respects. The infraorbital foramen is single and larger than those of 
the other species. The fourth premolar, while of the same constitution as 
that of MW. stius, is relatively much smaller, not equalling in the extent of 
its grinding face one column of the first true molar. The latter is pris- 
matic, and of usual form. Its external crescents are not produced as in B. 
simus, so that there are no distinct vertical ribs. 
Measurements. —~ M. 
Diameter-of last premolar { anteroposterior ........... .0050 
TANSVEISE eevee esc ae vs -0045 
Diameter of firsttrueimolar { anteroposterior......... .0080 
transverse... ........ oe. 0055 
This species was found with the three preceding in the Upper Miocene 
of Montana by my assistant, J. C. Isaac. 
BLAsTOMERYX BOREALIS sp. nov. 
This genus was defined by me in the fourth volume of the Report of 
Lieut. G. M. Wheeler to the Chief of Engineers, 1877, p. 350, as not cer- - 
