OSTEOLOGY OF CAENIVOEOUS DINOSAUKS. 



29 



First antiorhital fenestra (/')• — The first antiorbital fenestra is of large size, 

 beiag relatively larger than in either Tyrannosaurus or Ceratosaurus and by far 

 the largest vacuity in the skull. Its upper boundary is formed ])y the lachrymal 

 and maxillary, anteriorly bj* the maxillary, ventrally by the maxillary and jugal, 

 and posteriorly by the descending branch of the lachrymal. 



Secoi^d antiorhital fenestra (/"). — Tliis opening which is small, subcircular in 

 •outline lies wholly within the maxillary. 



Anterior nares (ex.n/ir.). — Tlie external narial openmg is elongate, oval in form 

 and is bounded above by the nasal and premaxillary bones; anteriorly by the pre- 

 maxillary; below by premaxillary and maxillary and posteriorly by the nasal and 

 maxUlarj'. In this specimen it has a length an tero -posteriorly of 118 mm.; a depth 

 at the center of about 40 mm. 



Fig. 16.— .\, Oblique .side view of brain case of Antrodemus valens Leibt, No. 57.53, A. M., N. H. J nat. size. B. the 



SAME VrtTH POSTFRONTAL AND SQUAMOSAL REMOVED; b.pl.pr, BASIPTETGOID PROCESSES; B.sp. BASISPHENOID; car. in, 

 CAROTID INTERNUS; Con, OCCIPITAL CONDYLE; f.m, FORAMEN MAGNUM; feJI.OT, FENESTRA OVALIS; Fr, FRONTAL; Op. 0, 



paroccipital; o.sp, alisphenoid; Pa, parietal; Po, posiorbit.\l complex; Pr.ot, prootic; P.sp, pkesphenoid; qu.cot, 



COTYLUS FOR QUADRATE; S.OC, SUPRAOCCIPITAL; Sq, SQUAMOSAL; tub. B.OC, TUBEROSITY OF BASIOCCIPITAL; tub. B.Sp, 

 TUBEROSITY OF BASISPHENOID; I, II, III, IV, V, VII, IX, XI, XII, FORAMINA FOR E.XIT OF CBANl.AL NERVES. PARAOCCIPITAL 

 REPRESENTED AS TRANSPARENT IN ORDER TO SHOW FORAMINA. BOTH FIGURES (AFTER OSBORN). 



Supratemjjoral fossa (s.tf). — The supratemporal fossae are of large size, espe- 

 cially when compared with those of Ceratosaurus nasicornis. Although these vacui- 

 ties are considerably larger than as represented tu Marsh's restoration of the top view 

 of the skull of that animal. This fossa in Antrodemus is bounded anteriorly by the 

 frontals, alisphenoid, and postorbitals; externally by the postorbital and squamosal 

 above, below by the prootic and exoccipital; internally by the parietal, prootic 

 and alisphenoid. 



The dental formula of Antrodemus valens Leidy as shown by a study of several 

 individuals: 



Upper jaw: premaxillary, 5; maxillary, 15 to 17; total, 20 to 22. 

 Lower jaw: Dentary, 15. 



