445 
ably correspond to the lines of pit organs of Amia and of certain 
Teleosts. 
One of the dorsal head lines is found as a rounded, oval, or comma- 
shaped spot immediately postero-mesial to the sixth pore of the supra- 
orbital canal. The second dorsal head line starts from the hind edge 
of pore 11 infraorbital and runs backward and mesially, in a short curve. 
The anterior line lies directly superficial to a slight but very evident 
depression in the frontal bone, the posterior line occupying a similar 
depression in the squamoso-parietal. Both these depressions are shown 
in both Mürrter’s (No. 10) and Huxuey’s (No. 9) figures of the skull 
of the fish. POLLARD shows the anterior one as a short branch of the 
supraorbital canal, and it is somewhat displaced, posteriorly, from its 
normal position, as I find it. The posterior line PoLLARD does not 
show. 
These two lines of pit organs are evidently, from their general 
positions, the homologues of the anterior and middle head lines of my 
descriptions of Amia. Their innervation has, however, not yet been 
determined. No indication whatever of a posterior head line could 
be found. 
Two of the cheek pit lines start close together, immediately an- 
terior to pore 8 preoperculo-mandibular, one of them running almost 
directly forward, and the other almost directly downward. The third 
cheek line lies considerably posterior and somewhat dorsal to pore 8 
infraorbital, and is almost exactly in the line, produced, of the posterior 
horizontal cheek line. The posterior horizontal line, and the vertical 
one, occupy a single depression in the outer surface of the preoper- 
culum, near its hind edge, the anterior line occupying a depression 
near the anterior edge of the same bone, the depression often extending 
forward on to the hind end of the maxillary. These three lines are 
clearly the homologues of the horizontal and vertical cheek lines of my 
‘descriptions of Amia. POoLLArD (No. 12, p. 548) says of the horizontal 
lines: “From the opercular canal in the middle of the preoperculum 
a rudimentary branch extends forwards in a groove in that bone. 
Anteriorly there are indications that it joined the infraorbital canal”. 
COLLINGE here describes and figures what he calls the operculo-maxillary 
branch of the preopercular canal. The vertical line was apparently 
not noticed by either of these two authors. 
| The ventral pit line is a short curved line on the ventral surface 
of the gular, or branchiostegal plate of its side of the head. It lies 
in a plane approximately midway between pores 4 and 5 preoperculo- 
