12 DINOCEKATA. 



Tlie number of this specimen, in tlie Catalogue of the Yale Museum, 

 is 1036, and in the following pages this number will be used to distinguish 

 this type from other individuals of the same species. Other important 

 specimens will likewise be designated by their catalogue numbers. 



The skull of Dinoceras mirabile is long and narrow, the facial portion 

 being greatly produced. The basal line, extending from the end of the 

 premaxillaries along the palate to the lower margin of the foramen 

 magnum, is nearly straight. The toji of the skull supports three, separate, 

 transverse pairs of osseous elevations, or horn-cores, which form its most 

 conspicuous feature, and suggested the name of the genus. The smallest 

 of these jn-otuberances are situated near the extremity of the nasals; two 

 others, nuieh larger, arise from the maxillaries, in front of the orbits ; while 

 the largest are iiiainly on the jnxrietals, and are supported b}' an enormous 

 crest, which extends from near the orbits entirely around the lateral and 

 posterior margins of the true cranium. These general characters are well 

 shown in Plate I, which represents the skull of the type specimen. 



There are no upper incisors, but the canines in the male are 

 enormously developed, forming sharp, trenchant, decurved tusks, which 

 were each protected by a dependent process on the lower jaws. The 

 premolar and molar teeth are very small. 



The orbit is large, and confluent with the temporal fossa. The latter 

 is of great extent posteriorly, but the zygomatic arches are only 

 moderately expanded. There is no post-orbital process, but in Dinoceras 

 mirabile, and in some other species, there is a prominence on the frontal 

 bone, directly over the orbit. 



The Nasal Bones. 



The nasal bones are greatly elongated, being nearly half the length 

 of the entire skull. They project forward over the anterior nares, and 

 overhang the premaxillaries. They are thick and massive bones, 

 especially in front, and are united together by a nearly straight suture. 



