26 CASE. [Vou. XIV. 
formation of the base of the skull, and separates the pterygoids 
for a greater distance than it did in Protostega. 
The guadrates are present in excellent condition; they are 
still connected with the pterygoids, which are in turn united 
with the imperfect palatines. The articular face for the 
quadrato-jugal is strongly developed, and stands on the summit 
of a prominent ridge. The anterior edge is thin and rounded 
in outline; near its inferior portion there is developed a short, 
stout process, which fits into a deep groove on the external face 
of the pterygoid. This process gave attachment to the colu- 
mellar plates or the cartilage of its lower end. This strong 
process of the quadrate is present in Dermochelys; in the 
Cheloniidae it is very slender, and may even be absent as in 
Lepidochelys. 
Near the anterior inferior portion of the inner side lies the 
groove which in connection with the groove on the petrosal 
forms the foramen for the external carotid artery. 
The condylar face is divided into two parts; one, the pos- 
terior, looking slightly upward and backward; the other saddle- 
shaped, and looking almost directly downward. The upper 
posterior portion of the bone shows a strong face for attach- 
ment with the squamosal. The most distinctive feature of 
the bone, and one which is shared with none of the other sea 
turtles as far as observed, is the manner of attachment to the 
pterygoid; the posterior portion of that bone reaches almost to 
the condylar face, instead of being separated from it by a con- 
siderable space. The quadrate stood at almost a right angle to 
the pterygoid (Pl. V, Fig. 6). . 
The stapes was comparatively a very large bone. The distal 
end of one preserved in the stapedial notch of the right quad- 
rate is larger than the same bone in a skull of Dermochelys 
twice as large as the skull here described. 
The pterygotds of both sides are present in fairly good con- 
dition, the internal edges only being broken and crushed. They 
are long, slender bones with rounded external edges, decidedly 
concave external margins, and with no trace of an ectopterygoid 
process. The posterior portion articulates far down on the 
quadrate as described, and the posterior external face shows a 
