382 EDWARD PHELPS ALLIS, JR. 
of Huxley’s maxillary and the pterygoid. Its ventral edge is 
in articular contact with a bone that Reis calls the postsplenial, 
and it is said that the arrangement of the tubercules on the 
outer surfaces of the dentary and articular show that the fish 
had thick lips (eine starke Lippenbildung), and that the angle 
of contact of the postmaxillary and postsplenial lay immediately 
posterior to the angle of the gape of those lips. Reis accordingly 
compares these two bones of Macropoma with the posterior 
upper and mandibular labial cartilage of the Selachii, and with 
the single labial of Polypterus. Zittel (87-90) accepts the 
homologies thus proposed for these bones, and my work strongly 
favors them in so far as they refer to the labial cartilages of the 
Selachii. Reis further considers these bones to be rudiments of 
a preoral visceral arch; but if they be such structures, one re- 
lated to the upper and the other to the lower Jaw, the mouth 
could not represent the coalesced mandibular visceral clefts of 
opposite sides of the head, for those clefts would le posterior to 
the labial cartilages, between them and the mandibular cartilages. 
The conditions in Macropoma were thus strikingly similar to 
those in the recent Polypterus, the only noteworthy differences 
being that the labial cartilage of Polypterus is replaced by bone 
in Macropoma and that there is a mandibular labial bone as well 
as a maxillary one. The retention of the maxillary one of these 
two bones, the so-called postmaxillary, and its fusion with the 
hind end of the maxillary would apparently give rise to the 
conditions found in the recent Apodes, while the development 
eof a labial fold, and the persistence of a cartilaginous labial, 
would give rise to the conditions in Polypterus, and if this be 
the origin of the bones in these fishes; then the maxillary 
bone of the Apodes must be the homologue of that bone of 
Polypterus. 
AMNIOTA 
In my work on Polypterus (Allis, 00), I concluded, as already 
several times stated, that the maxillary teeth of that fish were 
probably the homologues of the maxillary teeth of mammals, — 
the teeth of the latter animals then not being the homologues of 
the maxillary teeth of the Holostei and most of the Teleostei. 
