24 DINOCERATA. 



palatal foramina. Near tins point, the palatine plates are united by 

 suture on t])e median line, and this sutni-e is continued backward along 

 the palate until it meets with the median suture between the maxillaries. 

 The anterior palatine foramina are narrow lissures, roimded in front, and 

 separating- the lateral portions of the premaxillaries from the palatine 

 plates, as in Eqiins. The latter ])lates miite posteriorly by suture with 

 the adjoining maxillaries, as shown in Plate V, pm. 



The premaxillaries vary nuich in form in the different genera and 

 species of D'nioccrafa. Two of the princi])al forms in the genus Dhioceras 

 are shown in figures 26 and 27, page 26, and two of the genus Tinoceras, 

 in figures 28 and 29, on page 27. 



The Palate. 



In all the Dinocerata, the palate is very nai'row, and much excavated, 

 especially in front. The bony palate extends back as far as the last 

 upper molar, and in some specimens bevond it. Each maxillary 

 articulates with the corresponding preinaxillar\- by a sutm-e connnencing 

 on the palatal surface, in front of the large canine alveolus, and running- 

 just witliin the border of the alveolus to near the middle of its inner 

 margin. At this point, the suture turns inward, across the end of the 

 main branch of the premaxillary, and then obliquely backward, along the 

 posterior end of its palatine plate. The n)edian suture is continued 

 l)ackward, separating the maxillaries, to a point nearly opposite the 

 middle of the penultimnte molar, where the maxillaries join the palatines. 

 The maxillo-palatine suture is at first transverse, extending across the 

 palate nearlv t(^ the alveolar l)order of the maxillary, and is then continued 

 backward near this border, and around behind the last molar, whence it 

 turns outward, ;ind a.scends the side of the skull in the orbital region. 



The ]);ilatal surface of each maxillnrv is dee])lv excavated in front 

 between the canines, along the dii^stemn. and as far back as the second or 

 third premolar ; but on the median line these bones meet in a sharp ridge, 

 nearly on a level with the outer o)iposite border of the maxillaries. 



