ANATOMY OF THE HEAD OF THE GREEN TURTLE. 383 



ing the pharyngeal portion of the bone forms with it a 

 wide sulcus (sulcus ptern(jo-mmidibularis) [21]. The epi- 

 pterygoid [22] articulates with the epipterygoid process 

 laterally so as to continue the pedicular crest, with which 

 the pedicle of the quadrate articulates. 



The Epipterygoid (Os epipteriigoideum) [22 fig. 36) is 

 a relatively very small rod of bone of triangular cross sec- 

 tion, articulating by one face with the epipterygoid process 

 of the pterygoid, and by its upper end with the alispiirnoid 

 plate of the parietal ; these two articulations are true 

 sutures. Inferiorly ossification of the cartilage between 

 it and the pedicle of the quadrate has never been completed 

 and a more or less extensive gap occurs between the bones 

 in the macerated skull. 



The Basisphenoid (Os basipheiioideum) [Figs. 38 and 39] 

 consists of a quadrangular body [A], elongated tapering 

 rostrum [B], and paired basipterygoid process [Cj. The 

 anterior limit of the body is an imaginary line drawn 

 between the two postclinoid processes. The upper surface 

 of the body is deeply concave in both directions, (fossa 

 medullar Is). The postclinoid processes [1] are triangular 

 plates of bone, set on either side of the anterior margin of 

 the medullary fossa and overhanging the "purs sellac " [2; 

 of the rostrum. The base of each postclinoid process is 

 perforated by the abducent canal [3]. One each side behind 

 the base of the postclinoid process is an area [4] for articu- 

 lation with the prootic. Posteriorly [5] the body forms a 

 synchondrotic union with the basioccipital. In the mid 

 line the transverse occipital margin is raised to form the 

 anterior portion of the ovoid tubercle [6], whose major part 

 is situated at the transverse basiphenoid margin of the 

 cerebral surface of the basioccipital. Between the occipi- 

 tal and prootic surfaces the postero-lateral angles of the 

 body are beveled away to form a small otic surface [7]. The 



