22 ANATOMY OF A CHELONIAN. 



noted (28), and, thence, forward between the eyeballs 

 and close to the bones on the roof of this part of the 

 skull. 



31. If necessary, now boil the skull again until its 

 bones are readily separable. Then, working with the 

 articulated specimen beside you for reference, remove 

 the bones, one by one, in the order in which they are 

 described below ; as each is removed, and its boundaries 

 thoroughly ascertained, sketch it in on your outline 

 drawings (23). 



32. The post-frontal is an irregular, squarish bone 

 which forms most of the posterior margin of the orbit ; 

 it articulates with the frontal and parietal above, and 

 jugal and quadrato-jugal below. A long process reaches 

 back from its postero-inferior margin. 



33. Below the post-frontal and forming the posterior 

 margin of the orbit, is the jugal, squarish as seen from 

 the exterior, but sending inward a process which forms 

 part of the floor of the orbit and reaches internally to 

 the pterygoid. It is overlapped by the maxilla in front. 

 The jugal overlaps behind the bone next described. 



34. The quadrato-jugal bounds the anterior margin of 

 the tympanic cavity. It sends downward and back- 

 ward a slender process, which turns around the margin 

 of the ear-opening for a variable extent. Posteriorly it 

 joins the quadrate below and the squamosal above. 



35. Behind the tympanum is a conical cap of bone, 

 the squamosal, which covers a similarly shaped semi- 



