542 ALES: [Vor. XII. 
(No. 129, p. 229), any connection whatever with any other 
nerve. 
It is evident from the above references that the work on 
ganoids needs some revision. It is also evident that Polypterus, 
and probably Spatularia also, represent, in the arrangement of 
the ophthalmic nerves, a condition intermediate between that 
found in elasmobranchs and that in Amia and the teleosts. In 
selachians there is a relatively small ramus superficialis trige- 
mini, or no such nerve at all, as in Torpedo (No. 22, p. 62); a 
large ramus profundus ; and in Acanthias embryos and skates 
a portio profundi, represented in the former by a separate 
nerve, and in the latter by communicating branches from the 
profundus to the Gasserian ganglion. In Amia there is a large 
ramus superficialis, a remnant only of a ramus profundus, but 
a portio profundi well developed. In teleosts the remnant 
even of a ramus profundus has disappeared, and the portio 
profundi is completely fused with the ophthalmicus superficialis. 
The superficialis and profundus seem to vary in relative impor- 
tance directly as the number of terminal buds found on the 
top of the snout and head. In bony ganoids and teleosts 
those buds are there found in great quantity (No. 79, p. 69), 
while in elasmobranchs they are much less abundant. In 
Amia they are innervated by the superficialis trigemini (No. 3, 
p. 513) and in elasmobranchs they must be innervated in the 
same manner, for Ewart says that the profundus takes no part 
whatever in their innervation. The profundus in elasmobranchs 
is distributed, in part, to the tubes extending from the ampullae 
to the skin (No. 26, p. 527). The disappearance of these organs 
in Amia and the teleosts may account for the great reduction 
of the profundus in these fishes, while the retention of a closely 
related organ, the nerve sack, in cartilaginous ganoids (No. 79, 
p. 38) may account for the possible retention of the nerve by 
them. 
In Protopterus (No. 88, p. 296) there is a large ophthalmicus 
profundus and no ophthalmicus superficialis trigemini. From 
the profundus three important branches are sent upward and 
forward to the top of the head and snout, where they become 
associated with the ophthalmicus facialis. They, therefore, 
