MAXILLARY AND VOMER BONES OF POLYPTERUS 373 
This furrow is apparently found only in those fishes in which 
the premaxillary has that posterior prolongation in the labial 
fold, ventral and parallel to the maxillary, that has already 
been referred to, and it is associated with a premaxillary that is 
more or less protrusive. This suprapremaxillary furrow has a 
position markedly similar to that of the maxillary labial-flap 
furrow of Polypterus and Acanthias, and it is probably its 
homologue, but there may, nevertheless, be two distinctly dif- 
ferent furrows here. This suprapremaxillary furrow, the pos- 
terior prolongation of the premaxillary ventral and parallel to 
the maxillary, the transference of the teeth along the ventral 
edge of the labial fold from the maxillary to the premaxillary, 
and the acquisition of a protrusive premaxillary are apparently 
all correlated features and are distinctly characteristic of the 
higher Teleostei, for Sagemehl says (’84, p. 101) that this type 
of premaxillary is found in all of the non-physostomous fishes 
and in many of the physostomous ones, while the holostean type 
of maxillary is found only in the remaining physostomous fishes. 
There are thus, in the Teleostei, at least two distinctly dif- 
ferent secondary dental arcades in the upper jaw, the teeth in 
these two arcades being homologous, but the bones on which 
they are implanted totally different. Whether or not a third 
and still different arcade is also found in certain of these fishes, 
the Apodes, for example, I am unable as yet to definitely de- 
termine. These latter fishes are classed with the Physostomi, 
and Boulanger (’04) says that the premaxillaries are absent in 
all of them. Gegenbaur (’98, p. 357) says that these bones are 
present in the Muraenidae, but reduced, and fused with each 
other and with the vomer to form the anterior end of the snout. 
Smith Woodward (’01) also says that the premaxillaries are 
present in the Muraenidae, but he considers them to have there 
fused only with the ethmoidal rostrum. Maxillary bones are 
said by Boulanger to be present in the Anguillidae and certain 
other families of the suborder, but absent in the Muraenidae, 
and there replaced by the palatopterygoids. Smith Woodward 
considers these so-called palatopterygoids of the Muraenidae to 
be maxillaries, and J, in an earlier work (Allis, ’03), concluded 
