CYCLOPIDIUS 249 



typical of the whole family. P 1 ' 2 ' 3 are similar in both Leptauchenia and this genus, with the 

 posterior part well developed and the anterior moiety reduced, thus often giving the appearance of 

 obliquity in position. P 4 is remarkable in the great development of the posterior crest, which fills all 

 of the posterior basin. P 2 and P 3 exhibit a similar tendency, a progressive feature unusual in the 

 Merycoidodontidse but met with in the deer, bovid, and members of other phyla of artiodactyls. 



Cyclopidius simus Cope 1878 

 Pis. XXXVII, figs. 10-1 1 ; PI. XXXVIII, figs. 1-3 



Original Reference: Descriptions of new Vertebrata from the Upper Tertiary formations of the West. 

 Proc. Amer. Philos. Soc, XVII, pp. 221-222. 



Synonym: Brachymeryx jeliceps Cope 1878, juvenile. 



Probable Synonyms: Pithecistes brevijacies Cope 1878, probably female (old); P. decedens Cope 1884, 

 juvenile; Cyclopidius emydinus Cope 1884, probably male; C. heterodon Cope 1878, probably female; C. 

 incisivus Scott 1893, probably male. 



Type Locality: Smith River Valley, Montana. 



Geologic Horizon: Upper Miocene (Deep River). 



Types: Genoholotype, Cat. No. 8116 A.M.N.H., skull, with zygoma and about half the brain case sheared 

 away longitudinally. Paratype, Cat. No. 8117 A.M.N.H., left ramus, still partly in matrix. Both collected by 

 J.C.Isaac, 1877. 



Specific Characters: The skull is broad and depressed, with a short muzzle. In general it 

 averages a little greater length than that of Leptauchenia. The maximum expansion of the zygo- 

 mata is just in advance of the glenoid surface. The malar is extremely deep below the orbit, 

 exceeding proportionally all other members of this family. Its lower portion extends backward 

 almost to the glenoid surface. The squamosal portion of the zygoma is much weaker, is regularly 

 convex, and has a very gentle upward trend. Anteriorly this process does not extend as far as the 

 postorbital margin. The facial vacuities are very large, extending posteriorly nearly to a line 

 through the middle of the orbits. They are shaped like longitudinally narrowed ovals. The 

 anterior supraorbital portions of the frontal form a rough tripod with the nasal bones. These are 

 very narrow and short, convex transversely, and together they form a blunt V-shaped wedge in the 

 frontals, just a little behind the terminations of the facial vacuities. The lacrimal bone is small 

 facially and bears a well-defined fossa. The frontals are of less diameter anteroposteriorly than 

 transversely and are depressed between the orbits, except for a low ridge along the median suture. 

 The orbits are closed, and the postorbital process of the malar is very wide anteroposteriorly, while 

 that process of the frontal is quite markedly weaker. The orbits are nearly round and well elevated, 

 with convex superior borders. The temporal ridges converge gradually and meet just back of the 

 postorbital constriction to form a long, thin, but not very high sagittal crest, which is very shallowly 

 bifurcated posteriorly. The supraoccipital crest overhangs slightly beyond the posterior edge of the 

 occipital condyles, and the prominent exoccipital crest is transverse. The brain case is narrow and 

 moderately elongate, with a small ridge along the parietosquamosal suture. The external auditory 

 meatus is quite large, with external opening elevated, and its direction is mainly backward, but also 

 a little outward. The V-shaped palatonarial border is opposite the posterior edge of M 3 . The 

 palate is wide and moderately vaulted. The basicranial axis is shallow and the glenoid surface 

 gently convex. The transverse extent is restricted by the bulla, which extends forward almost to the 

 line of the anterior border of the glenoid surface. Cope ( 1 884B, p. 549) wrote: 



The internal extremity of the glenoid cavity is concave, and the surface descends, forming a robust peduncle, 

 as large as the postglenoid process, to which the anterior part of the otic bulla is attached. This is a character I 

 have not seen in any other species of the family. 



In a Marsh specimen of Leptauchenia major, Cat. No. 10118 Y.P.M., there is a small anterior 

 process on the bulla, much like that in the C. simus holotype, which does not seem to connect with a 

 peduncle from the glenoid but rather with the pterygoid bone. The connection is broken, however, 



