140 



TRANSACTIONS OF THE AMERICAN PHILOSOPHICAL SOCIETY 



transversely into broad wings. The basisphenoid is squeezed between the eye muscles 

 into a narrow but strong median brace, which extends obliquely downward and forward 

 to support the parasphenoid. Behind this junction the myodome or eye-muscle chamber 

 is very capacious. It extends back beneath the otic region but does not open posteriorly. 

 The lateral surfaces of the prootic,' pterotic and sphenotic together bear the usual wide 

 facet for the head of the hyomandibular (Figs. 31, 32). On the inner side the pterotic and 



facet for 

 hyom. 



soc 



lattemp-fos 

 m.dilat.op...... 



fpost.temp.fas. 

 mm.lTap.etc. 



subTemp.fos 

 \'^^ (rn.leuphar. ) 



(trigemino-facialis recess) 

 soc 



myodome 



-foK.hyp Y-Vll ^°^- ^J'P 



Fig. 32. Tarpon atlanticus. Neurocranium. 



A. Neurocranium with sagittal section of cranial vault. 



B. Diagram of medial aspect of membranous labyrinth, based on data from Retzius. 



C. Neurocranium, outer surface. 



