xo. IGOO. OtiTEOLOGY OF CAMl'TOiiAVRVti^UlLMORE. 215 



dorsal process between the thin inner and onter walls, and Avhich 

 opens posteriorly. The foramina, in passing through the outer wall, 

 are directed obliquely backward and appear to leave the maxillary 

 posteriorly throngh a conunon channel or groove on the superior 

 surface of the inner shelf-like projection of this part of the bone. 

 This is well shown in the left maxillary of Cat. No. 5818, U.S.N.M. 

 Thev probably transmitted the nerves and blood vessels leading to the 

 lips. Above this row are still other irregularly placed foramina as 

 shown in fig. T. The slightly concave dentigerous surface in No. 

 ]8S() has alveoli for 16 teeth. In advance of the most anterior tooth a 

 thin, flattened process is sent forward which underlies the posterior 

 ascending process of the premaxillary. Viewed from above the maxil- 

 lary remains about the same width throughont the median part, but 

 the inner border of the posterior end is diagonally truncated. On 

 the internal side just above the tooth row is another series of 

 foramina Avhicli probably transmitted nerves and nourishment to the 

 teeth. 



4^ 



FlO. 7. LATERAIi VIEW OF LEFT JIAXILLARY OF CAMPTOSAURIIS. NO. 188G, YALE MuSEtTM. 



J NAT. SIZE. 



The exact relationships of the maxillary to the surrounding ele- 

 ments can not be determined further than what is shown in fig. "2. 



EXTERNAL OPENINGS IN THE SKULL. 



Foramen Tnagnum. — The foramen magnum is large as compared 

 with the size of the brain cavity, suboval in outline, being wider above 

 than below, the longer diameter being vertical. It is bounded below 

 by the basioccipital, on either side by the exoccipitals, and above by 

 the supraoccipital (see fig. 4, fm.). 



Sujjratemporal fossce.—'Th^ supratemporal fossae are situated one 

 on either side of the parietals. The}^ are bounded anteriorly by the 

 postfrontals and parietals; internally by the parietals; posteriorly 

 by parietals and squamosals; externally by the squamosals and a pos- 

 terior prolongation of the postfrontals. These openings are propor- 

 tionately much larger and more elongate than in Stegosaurus. 



Hapraorlntnl fossa. — The supraorbital fossa is bounded anteriorly 

 by the prefrontal and supraorbital ; posteriorly by the postfrontal ; 



