RL. 
acquire primary relations to the skull and become the primary ethmoid 
of Teleosts, as SAGEMEHL asserts. Nothing in my work so far, gives 
positive evidence either for or against this assumption. 
The posterior portion of the canal component of the premaxillary 
bone of Polypterus is certainly the homologue of all or a part of the 
antorbital of Amia. 
Having left the premaxillary the infraorbital canal of Polypterus 
enters and traverses a bone called by TraquAır the anterior suborbital 
bone, the homologue, probably, of the lachrymal of Amia. In this 
bone the canal has a slightly curved course, running at first upward 
and backward, and then downward and backward. In this bone there 
is a single sense organ, the fifth one of the infraorbital line, and be- 
tween the bone and the next following one there is the sixth tube of 
the line. This tube is a short one, like the next preceding one, and 
also like all the following ones in the line, and opens on the external 
surface of the head by a single pore that lies immediately ventral to 
the eye, somewhat anterior to its middle point, the pore, like the 
preceding one, and like the next following one also, lying immediately 
dorsal to the deep furrow in the upper lip of the fish. 
On leaving the lachrymal the canal turns still more downward 
and enters the maxillary bone of Traquaır’s descriptions. It then 
turns backward in this bone, then backward and upward, and leaves 
the bone near the dorsal edge of its postorbital portion. In this 
maxillary section of canal there are two sense organs, the sixth and 
seventh of the line, and between these two organs the seventh tube 
of the line is given off. It is a short tube that opens immediately 
on the external surface by a single pore, the pore lying ventral to the 
hind edge of the eye. The canal component of the maxillary bone of 
Polypterus is thus formed by the fusion of two lateral-sensory ossicles. 
The posterior ossicle, both in general position and in its relation to 
the anterior horizontal cheek line of pit organs, to be later described, 
corresponds to the lower, or first postorbital bone of Amia. The an- 
terior ossicle is a suborbital one, and there is but one of these ossicles 
in the fish, instead of two, as in Amia. 
The eighth pore of the line is a large one that lies a considerable 
distance behind the eye, in a line, approximately, with its ventral edge. 
It opens by a short tube into the canal as it passes from the maxillary 
to the posterior suborbital bone of TrAquAır’s descriptions. The canal 
then turns upward in the latter bone, and leaving it as its dorsal edge 
enters the postfrontal bone of TRAQuatr’s descriptions, which it tra- 
verses, running backward, upward and mesially. In each of these two 
