Case.] Turtles. 373 



the posterior border of the temporal roof, much deeper than in 

 Chelonia. 



The supraoccipital is comparatively short and stout. It ex- 

 tends well forward under the parietals, and has a short, strong, 

 posterior process, with a deep groove on its inferior face. The 

 superior surface of the process is nearly straight, and presents 

 no trace of the strong convexity shown in T. serrifer. 



The vomer is broad and strong anteriorly, with a concave in- 

 ferior face. This expanded anterior portion, together with the 

 maxillaries, forms the anterior edge of the posterior nares. At 

 the anterior end of the nares the bone contracts sharply, and 

 sends back a long, flat process to reach the posterior end of the 

 palatines. On this process is developed a strong ridge, becom- 

 ing obsolete as it approaches the posterior end, which separates 

 the posterior nares. These nares are oval in outline, and lie 

 well forward. There is no tendency towards a cover for these 

 on the lower surface by an expansion of the vomer or palatine, 

 as in the recent sea turtles. 



The palatines are broad, thin plates of bone, attached by the 

 anterior part of their lateral edges to the maxillaries. Just in- 

 ternal to this suture there is a strong antero-posterior rugosity, 

 which does not rise above the level of the alveolar surface. 

 From the edge of this rugosity the bone bends upward sharply, 

 and is excavated to form the posterior nares. Posteriorly the 

 bone expands and becomes thin and plate-like. Above the 

 vomer, the posterior border of the palatines clasps the anterior 

 margin of the pterygoids. The external margin of the posterior 

 portion is excavated, to form with the maxillae a large foramen 

 — the palatine foramen — which is completed by the pterygoids 

 and jugals behind. This foramen is about two centimeters 

 long by one broad. 



The pterygoids are firmly united on the median line on their 

 anterior half. The anterior extremity is underlaid, and pre- 

 vented from appearing on the roof of the mouth by the vomer. 

 From near the anterior extremity, they send out lateral proc- 

 esses to join the jugals. Posteriorly each sends a broad and 

 long process to articulate with the quadrate. The distal end of 



