22 BULLETIN 110, UNITED STATES NATIONAL MUSEUM. 



suture. The inner side of this process is longitudinally grooved for articulation 

 with the process on the opposite maxillary. 



On the inner side of the ascending process and between the antiorbital fenestrae 

 this process develops an inward extension that stands at right angles to the longer 

 diameter of the process. It is perforated just above its junction with the body of 

 the maxillary by an elliptical foramen apparently establishing a connection between 

 the antiorbital fenestra. 



On the superior border of the posterior branch the surface is roughly striated 

 antero-posteriorly, evidently indicating the point of union with the palatines. 



The greatest length of the maxillary is 360 mm. . Osborn in the paper previously 

 cited gives the length in the American Museum specimen as 460 mm., but this is 

 evidently a mistake as the illustrations accompanying that article show it to be 

 about 378 mm., which represents an adult specimen. 



The series of alveoli measure 292 mm. in length. These decrease in size from 

 front to back, and are separated from one another by exceedingly thin bony 

 partitions. 



Jugal (j.). — The jugal is an exceedingly thin (transversely) triradiate bone 

 (fig. 13), its median portion forming the lower boundary of the orbit. The anterior 

 end is greatly expanded dorso-ventrally and laps along the outer sides of the lachry- 

 mal and maxillary. The tapering superior process joins by squamous union with 

 the descending process from the postorbital complex, the two forming the postorbital 

 bar which separates the orbit and lateral temporal fossa. Its manner of articulation 

 with the quadratojugalis described under that heading and need not be repeated here. 

 The jugal in Antrodernus is relatively longer than in Tyrannosaurus , and is heavier 

 than the same bone in Ceratosaurus. The right jugal in No. 4734 has a greatest 

 length of about 295 mm. and a greatest height at the center of 144 mm. 



Quadratojugal (qj.). — The quadratojugal joins the quadrate by a vertical suture 

 along its inner posterior side, the median portion of the border being free forms the 

 outer boundary of the quadrate foramen. This bone sends upward a moderately 

 broad superior plate that joins, externally, by squamous suture, with a descending 

 process from the squamosals as shown in figure 2 on plate 4. This quadratojugal 

 of Antrodernus may at once be distinguished from the same bone of Tyrannosaurus 

 by its narrower superior plate and its more rounded proximal extremity as com- 

 pared with the broadly expanded and squarely truncated end in the latter genus. 

 This plate is, however, somewhat shorter and also broader antero-posteriorly, than 

 in Ceratosaurus. 



The transversally flattened inferior process is directed forward and forms the 

 great part of the lower boundary of the lateral temporal fossa. This bar is lapped- 

 along the ventral internal side by a slender tapering posteriorly directed triangular 

 process of the jugal. Shown in figure 2 on plate 4, as being depressed slightly out 

 of position. The forward end of the inferior bar of the quadratojugal divides into 

 two spurs between which is received a portion of the upper posteriorly directed 

 process of the jugal, these form a strong union. of the bones at this point. The 

 flattened internal spur, (fig. 13), extends somewhat further forward than the external 

 spur (figs. 1 and 2 on pi. 4). The greatest length antero-posteriorly of the inferior 



