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PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 60. 



ing, but at the break it is triangular in section. On the ventral 

 and internal sides of the anterior half of the bone it is longitudinally 

 grooved for articulation with the ectopterygoid, maxillary, and pala- 

 tine bones. 



LOWER JAW. 



Both rami of the lower mandible are fairly well preserved, except 

 for the loss of the anterior halves of the dentaries. In their general 

 proportions, relative extent of the various elements, and the manner 

 of articulation of the component bones they closely resemble the 

 rami of Varanus, the chief differences noted being the shorter but 

 heavier expanded posterior extension back of the cotylus of the 



Fig. 12. — Left ramus of Saniwa ensidkns Leidy. Type, No. 2185, U.S.N.M. Natural 

 SIZE. A, EXTERNAL VIEW ; B, INTERNAL VIEW ; ung, ANGDLAu ; art, articular ; Cj 

 coEONOiD ; d, dbntary ; a, splenial ; sur, surangdlab. Anterior end of dentart 

 restored from Varanus. 



ramus and the relatively narrower (vertically) posterior end of the 

 dentary in Saniwa. 



Dentary. — Viewed laterally the dentary joins the surangular by 

 a nearly straight vertical suture at a point very slightly posterior of 

 the center, as in Varanus. The union of these two bones, however, 

 is not as weak as it would first appear, for the surangular extends for- 

 ward on the inside of the dentary, thus forming an effective and 

 strong articulation. Dorsally it meets the coronoid and ventrally 

 the small angular, which sends forward a short process that is 

 wedged in between the dentary and the splenial. The latter bone 

 laps along the inner side of the dentary, covering the V-shaped man- 

 dibular fossa of that side. 



Viewed from the side the dentary narrows toward the front. Near 

 its posterior end the bone is perforated, as in Varanus, by a large 

 oval foramina. Smaller perforations at intervals form a row imme- 

 diately below and parallel to the dental border (see A, fig. 12). 



