E. H. Barbour — New Longirostral Mastodon. 529 



above ; the pit small. All sutures are obliterated save those 

 bounding the malar. The basicranial elements, the palatine 

 roof, and the incisive sheaths are not deflected but are in the 

 same plane. The occipital condyles are as large as those of the 

 mammoth, which they resemble. The cranial walls are strik- 

 ingly thin, and the air-cells greatly reduced both in size and 

 number. They do not extend to all parts of the skull as they 

 do in mammoths and modern elephants. They are wanting 

 altogether in all portions of the zygomatic arch. The malar 

 portion of the zygoma is relatively slender and weak ; the 

 maxillary portion heavy and strong ; the postnarial aperture 

 is disproportionately small. The temporal or squamosal pro- 

 cess is very broad, heavy and strong, the condylar portion pre- 

 dominating. It exceeds that of the mammoth itself. The 

 condylar articulation is upon the anterior border. The post 

 glenoid portion is a thin, sharp ridge pendant from the 

 flattened occiput. The glenoid fossa is located at the base of 

 the post glenoid ridge and runs into the external auditory 

 meatus, which is located close upon the basioccipital. It is 

 interesting to note the progressive migration of the meatus 

 from a central position in our early proboscideans to one at 

 the circumference in modern forms, and to observe the gradual 

 arching over and union of the squamosal ridge and the post 

 glenoid, as in the Indian elephant. 



The infraorbital foramen is encased in a sheath twice as long- 

 as that of E. cohimbi. The incisive sheaths are very short. 

 The tusks though short are impressive because of their size and 

 shape. They are 4 inches in diameter but expand noticeably 

 toward the middle of the tusk and then contract to the pointed 

 tip. On the under side they are produced to a blunt ridge : 

 so a section is an acute, inverted ovoid. The enamel band is 

 uncommonly broad, 2|- inches. In the Nebraska Tetrabelodons 

 the inaxillo-premaxillary suture seems to run in a nearly straight 

 line paralleling the axis of the tusk and does not curve under 

 as in E. ijidicus. 



The University of Nebraska, 



Lincoln, Nebraska, March 15, 1916. 



