440 
line, this organ and the tenth one lying, approximately and respectively, 
opposite the posterior and anterior edges of the spiracular opening. 
The so-called parietal bone thus lodges two sense organs of the main 
infraorbital canal and is traversed by a section of that canal. Because 
of its being so traversed, van WIJHE (No. 15) proposed for the bone 
the name squamoso-parietal, which I adopt as POLLARD did before me. 
On leaving the squamoso-parietal the canal enters and traverses 
the second supratemporal bone of TrAaQuAır’s descriptions, near its 
lateral edge. In this section of canal there is no sense organ. At 
the hind edge of the bone, between it and the first supratemporal bone, 
is the twelfth tube and pore of the line. Opposite this tube the supra- 
temporal commissure arises, the tube and pore accordingly being double 
ones, formed by the fusion of the infraorbital tube and pore with the 
lateral, terminal tube and pore of the commissure. This pore and tube 
correspond to system 18 infraorbital of Amia, the development in Amia, 
however, being such that the terminal pore of the commissure, in that 
fish, does not fuse with pore 18 infraorbital, being, instead, enclosed 
in the infraorbital canal, as it closes, and opening directly into that 
canal between tubes 18 and 19 of the line. 
The canal, posterior to tube 12, enters and traverses the first 
supratemporal bone of TrAaquAır’s nomenclature, and then the post- 
temporal bone, in each of which there is a single sense organ. The 
thirteenth pore of the line opens into the canal between these two 
bones; and at the hind edge of the posttemporal bone is the fourteenth 
pore, this pore being a terminal one. No canal or section of canal is 
found posterior to it, the lateral line of the body being represented 
by surface organs only. 
The eleventh pore of the main infraorbital line opens on the bare 
surface of the squamoso-parietal. The twelfth, thirteenth, and four- 
teenth pores lie in the narrow band of tough dermis that lies between 
the postspiracular ossicles, on one side, and the supratemporal and 
posttemporal bones, on the other. The twelfth poré, in the 44-cm 
specimen, lay opposite and near the hind end of the first postspiracular 
ossicle. The thirteenth and fourteenth pores lay, respectively, opposite 
the anterior and posterior ends of the fourth postspiracular ossicle. 
The relations of these several pores to the series of spiracular ossicles, 
in this specimen, thus differ from that shown by both TRAQUAIR and 
CoLLINGE, and it may be added that the number of bones in the pre- 
and post-spiracular parts of the series also varies in different specimens, 
as BrıDGE (No. 7) has particularly stated. 
The three supratemporal bones on each side of the head of Polyp- | 
