Herrick, Nerves of Siluroid Fishes. 217 
of the nasal bone. This bone contains two sense organs sepa- 
rated by a pore, and in the space between the nasal and the 
frontal there is a third pore. In the frontal bone there is a 
pore between the third and fourth organs, and between the 
fourth and fifth organs this canal communicates with the infra- 
orbital. At this point there are four diverging canals; viz., 
the infra-orbital, directed ventrally, the main canal running back 
into the trunk, the supra-orbital, directed forward, and 
a short limb of the supra-orbital running backward and 
inward. This short canal opens by a pore at the caudal 
end of the frontal bone and contains a single sense organ, 
which I term the fifth supra-orbital organ. There is no pore at 
this point of union of the canals nor at any other place be- 
tween the fourth and fifth supra-orbital organs. The first four 
organs are innervated by the r. ophthalmicus superficialis fa- 
cialis, the fifth by a twig arising from the dorsal lateralis 
ganglion of the facialis just caudad of the origin of the r. oticus, 
which also supplies a row of large pit organs (Fig. 1, a. 4) 
which continue the direction of this canal caudad and mesad 
and which agrees closely with the anterior pit line of ALLIs’ 
descriptions of Amia. This short canal is present in identical- 
ly the same relations as regards position and innervation as in 
Amia (ALLIs, ’89) and in the siluroids described by PoLtLtarp 
(92); viz. Clarias, Auchenaspis, and Chaetostomus, save that 
in these siluroids it arises from the supra-orbital canal in front 
of its point of union with the infra-orbital, and in Clarias its 
terminal pore is pushed back a short distance into the squamo- 
sal. Batrachus has a single sense organ in the corresponding 
position and with the same innervation (CLapp, ’99), though 
here it is not enclosed ina canal, and a similar pit line has re- 
cently been described in Polypterus (AtLis, 00). In all of 
PoLLaRn’s cases this organ is innervated by a separate twig aris- 
ing, asin Ameiurus, directly from the ganglion. In Clarias, 
Callichthys and Chaetostomus PoLiarp states that the separa- 
tion of supra-orbital and infra-orbital canals takes place in the 
postfrontal bones instead of the frontal, as here. The supra- 
orbital canal does not communicate with any other canal, nor 
