540 (yan, 18, 
Measurements of Skull. M. 
Depth of malar bone at middle of orbit............... .0195 
he “« zygomatic process at glenoid fae (greatest).. .021 
Width of top of muzzle at larmier.......... Heenan ahi lindy) 
“«. ‘at middle of supraorbital border. ..........+..+ 051 
i MC MAIAT DONE... cererecoeavoeseevvace hein ein te O77 
is “« zygomatic processes of squamosal. ....+.++.+ 0795 
of occipital Condyles., 266s. ss eee rece ete ones yea a) 
Elevation of occiput, including condyles......++0+++++ .054 
Width Of occiput at middle vi. ae eee ee oe fi i UOb 
Depth skull at right angles to profile, at glenoid oa . 046 
bh (i i We “ hee orbit. seer veces 049 
hi sy Wie " “« Jarmier, exclu- 
RIVE OF LOCUy evils esse leni twenty ties eres ratte yeu | Uae 
Depth of mandible at bondyle. UAC ARE ee abe in GUCE 
me My (UM, We COM COUG) it weld cals anode a wats UR 
ay bh bids ges i Pye plas I etl RE NAO) 
Length of superior dental series ...........cecseseaee . 60885 
vi TO BUPCTION PM Dice ey aleve: vue wy ois We ater TOLOU 
iy “i bh TOG Ueber WN ACU Wucdevnoty it eirpamieieletys 0470 
a Ohi Vn ha Mea Da AN Fas ARUN MHLW, LOLOO 
i vi Nd Game, COLO Wii Fab ues Hw ace Wa ie Oe 
yy CO MUMSTION Meet ds vii» vsepaiice CEE COS CROC MEN HA TLR 
ak an HLUs Ue pivier whl’ s 9 sa vib TMCR ELPA erat ima 0425 
My Obes! dental series... . 66.465 WAN ere EVOO 
iY Mtl My vy ey ROE | AG SHA SSF a Os 
The unique and beautiful specimen on which our knowledge of this 
species rests, was found in a formation of the Ticholeptus Miocene near 
Laramie Peak, Wyoming Territory, by my assistant, J. O. Isaac. 
Merychyus arenarum, sp. nov. Sub-species arenarum, 
This species was more abundant than the IZ leptorhynchus during the 
Ticholeptus epoch, if we may judge from the number of specimens which 
have been procured. I enumerate here the five most important, viz. : 
No. 1, A skull which lacks the muzzle as far as the preorbital fossa, and 
the palate as far as the third premolar, and which has the mandible com 
plete as far as the coronoid processes, and which is accompanied by fore 
and hind feet and other limb bones. No. 2, A muzzle and right side of the 
face including the orbit, with the entire dentition, including that of the 
premaxillary bone, and that of the right mandibular ramus as far as the 
second true molar inclusive. No. 8, A skull with a part of the mandible, 
of an immature individual, in which the last superior molar is just ap- 
pearing, and the last two temporary molars are in place, and which is ac- 
companied by a few bones of the limbs. No. 4, Palatal part of skull with 
nearly all the teeth, accompanied by perfect mandible with all the teeth, 
and a large part of the skeleton. No. 5, A skull from which the basi- 
