TEICLEIDUS SEELETl. 



lo3 



bears a deep median groove, at the bottom of which traces of the original 

 separation of the two bones can be seen. At the posterior end of the groove are two 

 deep depressions which seem to have received the anterior ends of the pterygoids. 



Test-fig. 74. 



Basis cranii and pterj^goids of Trichidus seeleyi, from below. (R. 3539, uat. size.) 

 hoc, basioccipital : hs., basisphenoid ; i.p.v., interpterygoid vacuity ; oc.c, occipital condyle ; j:>«s., para- 

 sphenoid ; 'p.p.v., posterior palatine vacuity ; pt., pterygoid ; xit.f., facet for posterior ramus of pterygoid ; 

 lyt.p., basisphenoid process of pterygoid ; pt.s., sutural surfaces of anterior ends of pterygoids, the 

 bones being separated through distortion ; i^r./., facet for union with quadrate. 



