366 EDWARD PHELPS ALLIS, JR. 
upon it, but it is, in this part of its length, wholly separate from, 
and independent of, the bone that encloses the overlying section 
of the laterosensory canal. Slghtly posterior to the anterior 
end of the palatoquadrate cartilage, this dental component of 
the maxillary bone loses its mesial, palatal extension, and then 
fuses with the overlying canal bone, the teeth now being implanted 
upon the so-formed bone, and that bone being separated from 
the lateral edge of the ectopterygoid by the primary alveolo- 
labial sulcus. The line of the maxillary continues to follow the 
line of the primary lip, and when the primary and secondary 
sulci fuse with each other at the anterior edge of the lateral 
process of the ectopterygoid, the line of the maxillary teeth 
comes into contact with the lateral edge of the ectopterygoid, 
as described in my earlier work (Allis, 00). These teeth lie 
wholly internal to the labial fold, and hence cannot have been 
developed in any relation to either of the upper labial cartilages. 
The maxillary and ‘premaxillary bones of Polypterus thus both 
have dental and facial components, which Gaupp says is char- 
acteristic of higher vertebrates, and they seem to certainly be 
the homologues of those bones. The maxillary bone of this fish 
is thus properly so-called, and as it and the teeth it bears are not 
the homologues of the bone and teeth of Amia, the bone and 
teeth of the latter fish should be otherwise designated, and I 
shall refer to them as. the holostean maxillary bone and teeth, 
and to the dental arcade of the fish as a premaxillolabial one. 
The so-called vomers occupy a position that corresponds, as 
already explained, to that of the palatine processes of the 
Selachii plus the palatine fold, and they are accordingly mesial 
dermopalatines. These bones and the teeth they bear were 
accordingly not developed, primarily, in any direct relation to 
the base of the neurocranium, differing radically in this from 
the parasphenoid. The anterior end of the basal plate of the 
latter bone of Polypterus lies in the roof of the depressed region 
between the vomers of opposite sides, that is, in the roof of 
what corresponds to the suprapalatine recess of the Selachii. 
The vomers of Polypterus lie, morphologically, in the floor of 
that recess, and they are, in my 75-mm. specimen, nowhere in 
