was 
the os terminale and accessory nasal represented by a single bone, 
this thus being one step in the more extended fusion found in Amia. 
The Supratemporal Cross-Commissure, as already stated, 
leaves the main infraorbital canal as it traverses the second supra- 
temporal bone, and traversing that bone and then the third supra- 
temporal bone joins, in the middle line of the head, its fellow of the 
opposite side. There is a sense organ of the commissure in each of 
these two supratemporal bones, and there are two tubes in the line: 
one leaving the canal between the second and third supratemporal 
bones, and the other leaving it in the middle line between the third 
supratemporals of opposite sides of the head. Each of these tubes opens 
on the outer surface by a single pore. 
The Preoperculo-Mandibular Canal begins anteriorly at 
a median pore common to it and its fellow of the opposite side. From 
there the canal runs backward in the dentary, having three sense 
organs in that bone and two tubes and pores. At the hind end of 
the dentary, between it and the angular of Traquaır’s descriptions, 
is the fourth tube and pore of the line. The canal then enters the 
angular, in which there are two sense organs, the fourth and fifth of 
the line. van WiJHE has proposed for this bone the name dermarti- 
cular, doubtless, in part, because of its enclosing a section of lateral 
canal, and I adopt the name, for that and other evident reasons. 
In the dermarticular, between the fourth and fifth sense organs, 
the fifth tube of the line arises. This tube, unlike all others in the 
lateral system of the fish, was, in my 44-cm specimen, a long one. 
It ran directly backward, superficial to the canal, in the dermal tissues 
covering the dermarticular, and opened into the sixth tube of the line, 
that is into the tube that issued from the canal as it passed from the 
dermarticular into the preoperculum, the term preoperculum being 
used as MULLER employed it. The sixth pore of the line was thus 
a double one, being formed by the fusion of the fifth and sixth pores 
of the line; and if the mandibular and preopercular parts of the line 
be considered as separate canals the tube and pore become triple ones. 
| In three smaller specimens that I examined the fifth and sixth tubes 
and pores had not fused, each tube being found as a short one, similar 
to the other tubes of the line, and in a normal position in reference 
to its point of exit from the main canal. 
| Beyond the double or triple pore No. 6 the canal, after traversing 
‚the dermis between the dermarticular and the preoperculum, enters 
the latter bone and traverses it its full length, lying in a thickened 
