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right nasal, on which it ends by a pore. It has only 3 
pores and 4 sense organs, omitting those in the commis- 
sure. It is curious to find that opposite the entry of the 
commissure there is a small blind diverticulum, containing 
no sense organs, and corresponding exactly to a similar 
structure found in the Cod (see fig. 23).* 
The Left Supraorbital (swp. c.’)—_Anastomoses with 
the left infraorbital just as on the opposite side, passes 
forwards within the left frontal for a short distance, and 
receives the commissure. Just opposite the latter point 
it gives off a surface pore below which may correspond to 
the blind sac of the ocular side. Between its anastomosis 
with the left infraorbital and reception of the commissure, 
it has one large sense organt but no pore (cp. other side, 
fig. 23). In front of the commissure the canal leaves the 
frontal, but still lies in a depression on it, and ends 
blindly a short distance anterior to the commissure. This 
description enables us to compare the condition in the 
Plaice with that of the Turbot, as described by Traquair, 
and to correct the latter’s figure of the Plaice in some 
slight particulars. The other supposed remnant of the 
left supraorbital canal, discovered by Traquair, is situated 
far in front on the ocular side of the body very near the 
dorsal edge and above but a little behind the anterior 
extremity of the right supraorbital (figs. 23 and 29, 
sup. ¢."). It consists of a very small follicle situated, 
according to Traquair, on a minute ossicle representing a 
greatly reduced left nasal, and containing two surface 
pores, and, according to our sections, one sense organ. 
* Cole, Trans. Linn. Soc., ser. ii., vol. vii., pp. 157 and 180. 
+ This sense organ, as well as the one on the left side of the supraorbital 
commissure, is innervated by the R. ophthalmicus superficialis vii. of the 
left side. This is quite a conspicuous nerve, in spite of the abortion of 
the greater part of its sensory canal. There can, therefore, be no question 
that these parts of the canal system belong to the supraorbital canal. 
