5IAKSH.] 



DIPLODOCUS. 



177 



indications of sclerotic plates have been found either in Diplodocus or 

 in the other genera of Sauropoda. 



The suprateniporal fossa is small, oval in outline, and directed upward 

 and outward. The lateral temporal fossa is elongated, and oblique in 

 position, bounded, both above and below, by rather slender temporal 

 bars. 



The prefrontal and lachrymal bones are both small; the suture con- 

 necting them, and also that uniting the latter with the jugal, can not 

 be determined with certainty. 



The postfrontals are triradiate bones. The longest and most slender 

 branch is that descending downward and forward for connection with 

 the jugal; the shortest is the triangular projection directed backward 

 and fitting into a groove of the squamosal; the anterior branch, which 

 is thickened and rugose, forms part of the orbital border above. 



The squamosal lies upon the upper border of the paroccipital process. 

 The lower portion is thin and closely fitted over the head of the quad- 

 rate bone. 



Fig. 27 — Sbull of IKplodociis long-us Marsh : seen from below. One-sixth natural size. 



6. basioccipital process; eo, exoccipital ; vi, maxillary; mp, maxillary plate; o, occipital condyle; 

 p, palatine; pm. premaxillary ; pt, pterygoid: pa, parasphenoid ; q, quadrate; t, transverse bone; 

 v, vomer. 



The quadrate is elongated and slender, with its lower end projecting' 

 very much forward. In front it has a thin plate extending inward and 

 overlapping the posterior end of the pterygoid. 



The quadratojugalis an elongate bone, firmly attached posteriorly to 

 the quadrate by its expanded portion. In front of the quadrate it forms 

 for a short distance a slender bar, which is the lower temporal arcade. 



The palate is very high and roof like, and composed chiefly of the 

 pterygoids, as shown above in fig. 27. The basipterygoid processes are- 

 elongate, much more so than in the other genera of Sauropoda. 



The TJterygoids have a shallow cavity for the reception of these proc- 

 esses, but no distinct impression for a columella. Immediately in front 

 of this cavity the pterygoids begin to expand, and soon form a broad, 

 flat plate, which stands nearly vertical. Its upper border is thin, nearly 

 straight, and extends far forward. The anterior end is acute and unites 

 aloDg its inferior border with the vomer. " A little in front of the middle. 

 16 geol, pt 1 12 



