112 
EDWARD PHELPS ALLtS. 
Elops and probably also in Belone. In certain other Teleostei 
the corresponding bone, the supra-ethmoid of current descrip- 
tions, was said to underlie a line of surface pit organs that 
corresponded to the canal line in Aniia. This supra-ethmoid 
bone was accordingly considered to be a bone of membranous 
origin that represented a deeper component of the canal- 
bearing bone of Amia, just as, in certain others of the canal- 
bearing bones of Amia and other fishes, there is au uuderlying 
membrane component apparently developed somewhat inde- 
pendently of the canal-bearing component. The conditions 
now found in Raia suggest that this supra-ethmoid bone 
of the Teleostei is represented in the nasal-flap cartilage of 
Raia. If this be so, the supra-ethmoid bone can not represent 
an underlying component of a canal-bearing bone, for the 
cartilage of Raia lies definitely external to the related canal. 
This origin of the supra-ethmoid bone from the nasal-flap 
cartilage might then account for the absence, in those fishes 
in which that bone is found, of the canal line found in Amia; 
for this cartilage, or bone, in sinking from the position which 
it has in Raia to that which it has in the Teleostei, would 
necessarily smother the uuderlying canal and ultimately lead 
to its complete abortion. The line of pit organs that over- 
lies the supra-ethmoid bone in certain Teleostei would then 
be a secondary outgrowth from the end of the infraorbital 
canal line, and hence not the homologue of the cross-commis- 
sural canal line of Amia and the other fishes in which it is 
found. In Amia, Polypterus, and Elops, it is to be especially 
noted that the presence of a canal-bearing ethmoid bone is 
associated with the relation of the maxillary bone to the pre- 
maxillary that Sagemehl (1884) described as lateral, and that 
is said by that author to be found in only a few of the 
Teleostei. These two conditions may accordingly be related, 
but the want of proper material does not at present permit me 
to farther investigate it. 
O 
Palais de Carnoles, Menton; 
January 20th, 1916. 
