460 F. vox HUEXE THE YOMER-PARASPHEXOID QUESTION 



pterygoids and in the middle and anterior portion by the bones which I 

 regard as the vomers. The pterygoid and the vomer are in contact. Be- 

 tween the greater portion of the vomer and the anterior extremity of 

 the pterygoid the palatines are interlocked. 



The internal nares are separated by a septum partly formed by the 

 vomers (posteriorly and above) and partly by the fnsed premaxillffi, 

 covering that part of the vomer from below. The lateral walls of the 

 internal nares are formed by the palatines. Between the pterygoid, 

 palatine, maxilla, and jugal the transversnm is situated. 



PrESEXTATIOX of THE IMPORTANT FaCTS 



These are the important facts. 



The bones which I regard as the vomers are separated by the ptery- 

 goids from the basisphenoid by the length of the entire basis cranii, and 



Figure 1. — Dicyno(Jon sollasi Broom. Right side. Natural size. 



are mainly situated just behind the internal nares. There is certainly 

 a long interspace between the basisphenoid and the vomers and this space 

 is occupied by the pterygoids. Therefore I can not adopt the interpreta- 

 tion of the paired vomers being in fact the parasphenoid. On the con- 

 trary, the true parasphenoid is present in the major portion of the 

 rostrum basisphenoidei. It is useful also to compare the sections given 

 by Sollas. It is quite true that the parasphenoid may extend for a 

 considerable distance anteriorly and that the vomer may extend far 

 posteriorly, but the main region of the parasphenoid is below and imme- 

 diately in front of the basisphenoid, and the main region of the vomer 



