614 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxvii. 



POLYMIXIA JAPONICA Giinther. 



The top of the head is slightly depressed in the region above the 

 alisphenoids. The frontals have each a thin bony tunnel, which opens 

 anteriorly at the nasals, and laterallv a short distance behind the pre- 

 frontal. A thin high ridge runs from the posterior end of the pterotic, 

 along the frontal, becoming low anteriorh^, and disappearing a little 

 in front of the orbital cavity or opposite the anterior end of the supra- 

 occipital crest. The supraoccipital crest rises well above the rest of 

 the cranium. The myodome is large and is continued backward as a 

 tube, which narrowh' opens to the exterior posteriorly under the end 

 of the parasphenoid. The anterior opening to the brain case is 

 unobstructed except b}" the orbitosphenoids, which narrowly bridge 

 the alisphenoids. The auditory bulla is moderate, not much project- 

 ing, and formed by thin polished bones. There is an area of cartilage 

 at the junction between the epiotic, the parietal, and the pterotic. 



Fig. 9.— Polymixia japonica. 

 For lettering see fig. 6. 



The posterior end of the basioccipital slopes toward the exoccipitals, 

 as is typical for the group. Its usual depression is at its upper edge, 

 and is inclined downward. The epiotics are but slightly covered by 

 the parietals. The surface to which the posttemporal articulates does 

 not project backward as a shelf. The supraoccipital comes between 

 the frontals as a long wedge, separating them for two-thirds of their 

 length. The opisthotics are well developed. They overlie the suture 

 between the pterotic and the exoccipital below. To their posterior 

 surface is developed a nodule, to which the lower limb of the post- 

 temporal is closely attached. The parasphenoid is rather wide. Pos- 

 teriorly it broadens out over the floor of the myodome and is articu- 

 lated broadly to the prootic, without leaving an open space, as in Beryx. 

 It reaches back and ends bluntly at the occipital condyle. The basi- 

 sphenoid has a slender descending process, which fails to reach the 



