en 
that part of the palatine process that lay mesial to the line of contact 
would be a hinderance to the free articular movements of the parts 
concerned, and that it would accordingly tend to become detached 
or resorbed; and if resorbed it would evidently leave a fold in the 
mucous lining of the mouth cavity that would strikingly resemble the 
maxillary breathing-valve of many teleosts. If it be the homologue 
of that breathing-valve, as I believe it to be, the presence of the little 
blocks of cartilage, or procartilage, said by PoLLarn (1895) to be found 
in the valve of certain teleosts would receive a wholly natural expla- 
nation, as would also the median longitudinal thickening of the valve 
said by Dauueren (1898) to be a constant feature in the teleosts 
examined by him. And the small hard eminences found by me (1900) in 
the valve of certain other teleosts would be rudiments of the teeth 
here found in selachians. 
When the selachian palatine process had acquired articular 
relations with the lateral edge of the solum nasi and the mesial portion 
of the process had been resorbed, as above set forth, there would 
remain a triangular, basal portion of the process somewhat similar 
to that actually found in Amia (Auuıs, 1897a); and the dermal 
teeth related to this lateral portion of the cartilage of selachians would 
persist in the dermo-palatine of Amia. In teleosts the dermo-palatine 
would be a strictly similar bone, the maxillary process of the bone of 
these fishes being a portion of the autopalatine developed im relation 
to the maxillary and premaxillary bones. 
In Polypterus I concluded, in an earlier work (Auuıs, 1900), that 
the so-called vomers were maxillary breathing-valve bones and not 
vomers, and, reasoning from teleosts to Polypterus, I further concluded 
that they could not be “palate bones” as they were said by Tra- 
Quaır (1870) to have been considered by JOHANNES MÜLLER. My 
present work leads me to consider them as mesial dermo-palatines, the 
lateral dermo-palatines of Amia and teleosts being represented on 
either side, in Polypterus, in the palatine portion of the so-called 
maxillary bone (Anus, 1900). There are thus, apparently, two 
distinctly separate dermo-palatine bones in Polypterus, and if the 
so-called maxillary bone of this fish is the homologue of the similarly 
named bone in higher vertebrates, it is evident that there is unfor- 
tunate confusion here in the use of the terms maxillary and palatine. 
In my work on Polypterus above referred to, misled by the posi 
tion of the breathing-valve in teleosts, attached to the internal su 
