FORT UNION OF CRAZY MOUNTAIN FIELD, MONT. 91 



the condylar foramen, apparently single as Broom says, although a 

 second opening may possibly have occurred along an adjacent broken 

 area. 



Farther anteromedial is another foramen, opening into a canal run- 

 nmg forward, probably for the carotid. Between these and the 

 temporal fossa is an elliptical opening on the skull as preserved elon- 

 gate anterointernal-posteroexternallj'. There is some bone exposed 

 at the posteroexternal end of this, not far from the posterointernal end 

 of the glenoid surface. This doubtless belongs to the auditory appara- 

 tus, but I cannot identify the elements. How this opening may have 

 been floored is not determinable, but I agree with Broom and differ 

 from Gidley in finding no evidence that there was an alisphenoid bulla. 

 Part of the bony internal wall of the vacuity is broken, revealing that 

 it contains a relatively large, gently curved, cavity, interpreted by 

 Broom as an uncoiled cochlea, a possible but not certain interpretation. 

 The anteroexternal rim of the vacuity is formed by a ridge continuous 

 anterointernally with the pterygopalatine crest, and posteroexternally 

 with the squamosal stalk attaching the glenoid (and zygoma). In 

 the lower surface of this ridge near its junction with the pterygopalatine 

 crest is a distinct foramen. Immediately above this, more in the 

 lateral cranial wall, is apparently another foramen, directed forward 

 and downward. The first of these openings does not, as Gidley 

 believed,^^ lead to an alisphenoid canal, and the two foramina together 

 probably represent the foramen ovale. Above and somewhat posterior 

 to the end of the palate, in the lateral cranial wall, is a large anterior 

 lacerate foramen. Separate rotund or optic foramina cannot be dis- 

 tinguished, and they are probably confluent with this fissure. More 

 anterior, at the same or a slightly higher level, above the anterior end 

 of M\ is a smaller foramen, probably the ethmoid or sphenopalatine 

 foramen. 



Mandible. — The rodentlike form of the mandible is well shown in 

 the figures. The symphysis is unfused.*^ The coronoid process is 

 feeble, somewhat recurved, and possibly pointed — it is not quite com- 

 plete in any specimen. The masseteric fossa is deep and bounded by 

 a strong flaring flange below. The pterygoid fossa is still more pro- 

 nounced and the pterygoid crest still more flaring. There is no angular 

 process. The dental foramen is at the bottom of the deep pterygoid 

 fossa, and the very small mental foramen is beneath the diastema. 



Vertebrae. — There are several vertebrae, but they are so poorly pre- 

 served that little can be made out beyond the suggestion, already 

 noted by Gidle}^, that neck and tail were both long and heavy. 



" He said (1909, p. 619), "there appears to be an alisphenoid canal", and I assume that he was referring 

 to this opening. 

 " Apparently it never fused in any multituberculate. 



