6 MEMOIRS OF THE CARNEGIE MUSEUM 



"The occipital condyle is hemispherical in form, and seen from behind is slightly 

 trilobate in outline. It is placed nearly at right angles to the long axis of the skull. 

 It is formed almost wholly of the basioccipital, the exoccipitals entering but slightly 

 or not at all into its composition. The basioccipital processes are large and rugose. 

 The paroccipital processes are stout and somewhat expanded at their extremities, 

 for union with the quadrates. 



"The parietal bones are small and composed mainly of the arched processes 

 which join the squamosals. There is no true pineal foramen, but in the skull here 

 figured (Plate II.) there is the small unossified tract mentioned above. In one spec- 

 imen of MorosauriLS a similar opening has been observed, but in other Sauropoda 

 the parietal bones, even if thin, are complete. The suture between the parietals 

 and frontal bones is obliterated in the present skull, and the union is firm in all the 

 specimens observed. 



"The frontal bones in Dlplodocus are more expanded transversely than in the 

 other Sauropoda. They are thin along the median portion, but quite thick over the 

 orbits. 



"The nasal bones are short and wide and the suture between them and the 

 frontals is distinct. They form the posterior boundary of the large nasal opening, 

 and also send forward a process to meet the ascending branch of the maxillary, thus 

 taking part in the lateral border of the same aperture. 



"The nasal opening is very large, subcordate in outline, and is partially divided 

 in front by slender posterior processes of the premaxillaries. It is situated at the 

 apex of the skull, between the orbits, and very near the cavity for the olfactory lobes 

 of the brain. 



"The premaxillaries are narrow below, and with the ascending processes very 

 slender and elongate. Along the median line these processes form an obtuse ridge, 

 and above they project into the nasal opening. Each premaxillary contains four 

 functional teeth. 



"The maxillaries are very largely developed, more so than in most other known 

 reptiles. The dentigerous portion is very high and slopes inward. The ascending 

 process is very long, thin, and flattened, including near its base an oval foramen, and 

 leaving a large unossified space posteriorly. Above, it meets the nasal and pre- 

 frontal bones. Along its inner border for nearly its whole length it unites with the 

 ascending process of the premaxillary. Each maxillary contains nine teeth, all 

 situated in the anterior part of the bone (PI. II., Fig. 1). 



"Along their upper margin, on the inner surface, the maxillaries send off" a thick, 

 ened ridge, or process, which meets its fellow, thus excluding the premaxillaries 



