354 DEEP SEA FISHES. 
tions of the fusiform glandular disks at the outer extremities of the 
nerves. 
An apparent departure from the common arrangement is that on Halo- 
saurus radiatus, Plate LXXXIV. figs. 3 and 5, but the difference is in the 
details rather than in the general plan, for though cranials, aurals, post- 
orbitals and spiraculars are perhaps without the glandular organs the 
canals are present and the minute nerve endings no doubt have their ordi- 
nary tactile functions. The most divergent feature in the system in this 
case lies in the backward extension of the oral in a short series of glands, 
similar to what obtains on Chaunax and corresponding to the canal on the 
Antacea known as the jugular, Plate LXX.7. On Halosaurus there is a 
further variation under the snout; and on Chaunax while the aural appears 
to be rudimentary there is an apparent connection between the rostral 
canals across the snout, the orbital is produced backward on the cheek to 
the spiracular, the latter is continued downward to the posterior extension 
of the oral which is continued still farther back toward the base of the 
pectoral, there are two connections between the orbital and the oral, the 
anterior being the angular (avg), and there is no postorbital. If it were 
not for the position of the vertical series on the cheek of Chaunax, so far 
backward from the orbit and behind the angular, it might be taken for the 
postorbital while the jugular extension would answer for the spiracular. 
In addition to the variations in the Lateral Canal System resulting from 
changes in the structure of parts of the fishes’ bodies adjacent to it there are 
others, consequents of changes in function; as on Phycis regius, Plate LX XXI. 
fig. 2, on which the system in the hinder portion of the cranial region has 
become rudimentary, probably on account of the acquisition by the species 
of an electric faculty. In this species the canals on the top of the head 
backward of the orbital are all affected by the change, and the origin of 
the shocks given by this fish may perhaps be traced to the aural portion 
of the head. Halosaurus also is a pertinent instance, since the system on 
the upper half of the head, where the nerve papilla (disks) are insignificant 
in size or invisible, apparently has the ordinary function of that on the 
head and body of a fish of the shoals, while in the canals of the lower half 
of the head the glandular organs are highly differentiated and evidently 
have taken on tbe office of luminous bodies and of flash lights. 
One of the most obvious modifications obtaining on bathybial fishes is 
that taking place in the organs at the ends of the nerves of the Lateral 
