1.254 DIt. EKIK A. STENSIO : NOTES 



concerned simply with the concavity filled with stone in the 

 posterior end of the pars basalis of the sphenoid, and that the 

 canal for the pituitary vein actually does not open there, but 

 runs somewhat in front of it, ventrally of the fossa hypo- 

 physeos, exactly as it does in Dictyonosteus. 



The foramen seen in Bryant's figures some distance in front of 

 the upper end of the basipterygoid process at about the middle 

 of the height of the sphenoid con'esponds approximately to the 

 external opening of the oculomotorius canal in Dictyonosteus^ 

 but a certain intei-pretation of it is not possible, as we do not 

 know the course of the canal leading medially from it, nor 

 several of the other canals of the region. It actually seems to 

 have a position somewha,t too far anteriorly to be the external 

 opening of the Canal for the ramus ophthalmicus profundus 

 trigemini and, on the other hand, too far back to be the external 

 opening of the opticus canal. 



The foramen which in Brya.nt's figures is seen in the anterior 

 part of the sphenoid ma}'' probably be the external opening of the 

 opticus canal. This interpretation is specially supported by the 

 fact that the eye has been situated far forward. 



No other foramina or canals that can be thought to have 

 transmitted the n. trochlearis, the r. ophthalmicus profundus 

 trigemini, the arteria carotis interna, and the v. cerebralis 

 anterior are described by Bryant, nor are any canals of this sort 

 clearly discernible in the figures he gives of the different 

 specimens, though they must of course exist. 



As is evident from the facts given here, the vena jugularis, th(^ 

 r. palatinus facialis, and the internal carotid artery must in 

 relation to the basipterygoid process have had the same course as 

 in Dictyonosteus. 



Of the primordial skeleton of the ethmoidal region of the 

 fish there is nothing to be added to what has already been 

 written above (p. 1253). 



Dermal Bones of the Prionordial Ne%irocran%%mi. 



The parasphenoid is, according to Bryant's description, 

 developed in the same Avay as that in Dictyonosteus and 

 Sauri'pterus (cf. Eastman, 1917, pi. vii. fig. 5), but is much 

 more narrow tha,n in these two forms. In my specimens there 

 are only fragments of it preserved. It is noteworthy that it 

 seems to be very firmly connected with the sphenoid. The 

 paired vomer seems to show the normal conditions. Nothing 

 of it is seen in my specimens. 



If, after these short remarks on the bones of the ventral 

 surface of the primordial neui"Ocranium, we turn to those of 

 the dorsal one (text-fig. 4), it is clear at once that Bryant has 

 correctly recognized the extrascapular bones, the parietal, the 

 supratemporal and the intertemporal, and it ought also to be 

 .added here that the sutures between the extrascapular bones 



