308 EDWARD PHELPS ALLIS, JR. 
the palatoquadrate, while the fold of Acanthias lies, throughout 
its entire length, posteromesial to that cartilage. There ap- 
parently is in Amia no fold that corresponds to the palatine 
fold of Acanthias. 
The vomer bones of Amia le posterior to the primary upper 
lip, and hence are ossifications in the roof of the buccal cavity. 
The dermopalatine is a lateral dermopalatine. 
POLYPTERUS 
In Polypterus there are, as is well known, thick fleshy upper 
and lower lips, each of which has the appearance of having been 
folded back upon the remainder of the lip. In my earlier work 
on this fish (Allis, 700), I considered these apparently folded- 
back portions of the lips to, alone, represent the maxillary and 
mandibular labial folds, but it was said that there were, internal 
to each of these folds, another smaller one. I now find that the 
so-called labial folds of these earlier description are simply labial 
flaps, apparently strictly similar to those above described in 
Acanthias, and that they and the so-called smaller folds that lie 
internal to them together form the entire labial fold. The folds 
and furrows of this fish must accordingly be fully redescribed, 
and for this purpose I have made use of serial sections of a 75-mm. 
specimen of Polypterus senegalus, certain of the sections being 
' reproduced in the accompanying figures 5 to 14. Figure 3 gives 
a lateral view of the head of a small adult Polypterus, with the 
mouth slightly opened, and figure 4 a similar view with the 
mouth forced widely open. 
The maxillary labial-flap furrow, which separates the maxil- 
lary labial flap, above referred to, from the remainder of the 
labial fold, begins immediately anteromesial to the nasal tube, 
encircles the Jateral edge of that tube and then continues pos- 
teriorly to the ventral corner of the labial cartilage, where it 
ends external to that cartilage. The maxillary labial flap, 
which lies external to this furrow, thus encloses no portion of 
the labial cartilage, and there is no other cartilage or bone en- 
closed in any part of it. Otherwise, the flap and furrow ap- 
parently correspond strictly to those in Acanthias, excepting in 
