No.3.) J7USCLES AND NERVES IN AMIA CALYVA. 629 
branches of the ophthalmicus superficialis trigemini in Amia 
embrace the ophthalmicus facialis. The nerve in Gadus has, 
contrary to the arrangement of the branches found in Amia, 
an intracranial course, as it has in siluroids, issuing on the 
top of the skull near its hind end. As the trigemino-facial 
ganglionic mass lies, in Clarias at least (No. 94, p. §29), inside 
the skull beside the brain, this difference of course is probably 
of no importance. 
In Clarias Pollard states that tube § of the infraorbital or 
main canal “must be regarded as the last rudiment of a canal 
represented in Amia by the vertical line of pit organs”’; that 
tube 6 ‘appears also to be the rudiment of a canal represented 
in Amia by the horizontal line of pit organs’’; and that tube 8 
‘corresponds to the rudimentary canal represented in Amia by 
the dorsal line of pit organs.” These conclusions are certainly 
wrong, for the canals of all the lateral lines are always formed 
in sections, each section inclosing an organ, and the tubes lead- 
ing to the surface from the developed canals always lie between 
two adjacent organs, and represent simply the fused open ends 
of two such sections (No. 3, p. 523). A sense organ is pri- 
marily never found in such a tube, and the tube can in no way 
represent a line of surface organs. The terminal tubes of a 
canal line may lie in the direction of such a line of surface 
organs, and may even inclose secondarily one of those organs, 
as is the case with tube 8 supraorbital in Amia (No. 3, p. 506). 
The tube has, however, in its development nothing whatever to 
do with the line and cannot represent it. A line of pit organs 
represents apparently the possibility of a canal; with the dis- 
appearance of the organs the possibility of the canal, even in 
rudiment, would certainly disappear. 
Pollard did not find any lines of pit organs in siluroids, and 
Collinge (No. 20) does not mention any. I, however, find 
them both in Amiurus catus and in Silurus glanis. In both 
these fishes there is an anterior crosscommissural line over the 
top of the end of the snout, and, two or possibly three lines on 
the top of the head; and in Silurus there are three lines on 
the side of the head. One of the lines on the top of the head 
is a direct continuation of the supraorbital canal, and in larvae 
