24 



BULLETIN 110, UNITED STATES NATIONAL MUSEUM. 



downward behind the head of the quadrate as in Ceratosaurus. An anteriorly 

 directed process meets the postfrontal, the latter being received in a deep elongated 

 groove on the external face. 



Posteriorly it rests upon the front upper border of the paraoccipital process. 

 Continuing inward it meets the base of the transverse portion of the parietal with 

 which it is suturally united. The longer axis of the squamosal in the articulated 

 skull is inclined somewhat forward from the vertical as shown in plate 4, figure 2. 

 Its greatest vertical extent is 175 mm. 



Ectopterygoid (ec. pt.). — In this specimen we are fortunate in having both 

 ectopterygoid bones present in a good state of preservation, though found dis- 

 articulated. Through the kindness of Messrs. Walter Granger and Barnum Brown, 



of the American Museum of Natural History, New 

 York, these bones were carefully compared with the 

 articulated elements in Theropod skulls of that insti- 

 tution, so that their proper position in the palate as 

 now articulated is to be relied upon as being accurate. 

 The ectopterygoid in Antrodemus is an irregularly 

 U-shaped bone formed by two posteriorly directed 

 branches, the more slender of which laps along the 

 inner side of the jugal. The larger one is directed 

 downward and backward extending well below the 

 border of the jugal, as in Splienodon. Along its pos- 

 terior side it is lapped by a descending branch of the 

 pterygoid, which in Ceratosaurus extends to the lower 

 end of this process, and following that evidence it 

 has been so restored in the Antrodemus skull. On 

 the anterior internal side this bone develops a thin, 

 curved, wing-like process that overlaps a convex ex- 

 tension of the pterygoid, as indicated in figure 14. 



Pterygoid (pt.). — The pterygoids are represented by a considerable part of the 

 central portion of the right element. The left is missing. A thin, Vertical process 

 extends backward and outward from its articulation with the basisphenoid proc- 

 esses and unites with the inner and forwardly directed plate-like extension of the 

 quadrate (fig. l). A horizontal process extending forward and outward from the 

 same point of attachment underlaps the ectopterygoid and sends downward and 

 backward a slender process that reaches the full length of a similar ventral process 

 of the ectopterygoid. 



The relations of the pterygoids to the other bones of the palate in Antrodemus 

 are unknown at this time. 



Fig. 14.— Right ectopterygoid of Antro- 

 demus valens 1.EIDY. No. 4734, U.S.N.M. 

 Viewed from above. J nat. size, a, 

 Border lapping along inner slde of 

 jugal; b, side which joins the pterygoid 



