360 DEEP SEA FISHES. 
groups. Collinge and others also have made attempts in similar directions 
placing the stress mainly upon the innervation. Though the distribution of 
the nerves can be used to advantage in connection with the higher divisions, 
in an approach to the species and varieties it becomes less practical than the 
more obvious features, the arrangement and special characters of the system 
itself. It is in the numbers of the disks, their distribution, and the compar- 
ative sizes and degrees of development that the most effective aids to classi- 
fication are available; it is by means of these that most light is shed upon 
the closer and more recent affinities among deep sea fishes. 
In the following notes attention is directed to a few of the more obvious 
special features of each of twenty-six species of Teleosts from which outlines 
of the cephalic portions of the system are presented. 
Ectreposebastes imus, Cottunculus Thomsonit, and Hoplostethus pacificus of 
Plate LX XI. illustrate three types of the canals on the cheek behind the 
eye: in the first the orbital and the spiracular are reduced to a single canal, 
in the third they are distinct though tolerably close together, and in the 
second they appear to be partially reduced. The aural branches of the first 
and the second are transverse though they may not unite across the occiput, 
but on the third they evidently unite with the frontal branches of the 
cranials and form a loop, as in Lamprogrammus, ‘The disks are small and 
nearly uniform in size in each case; they are more developed than those of 
the shoalwater allies; on the head Z. imus has 52, C. Thomsonii has 56, and 
LH. pacificus has 70. 
Caulolepis subulidens and Melamphaés ngrofulvus, Plate LXXII., though 
differing in details, show considerable evidence of relationship. The post- 
orbital and spiracular branches of the canals are distinct; the frontal 
branches and the aurals are similar, but the latter bear two disks on Melam- 
phaés and only one on Caulolepis. The probability is in favor of an aural 
commissure on the occiput on both forms, and it may be the frontal 
branches are connected with the aurals; these connections have not yet 
been made out. The disks of Caulolepis appear to be rather more complex 
than those of Melamphaés; C. subulidens has 72 disks on the head and 
M. nigrofulvus has 68. 
Chaunax coloratus and Lepophidium emmelas, Plate UXXIIL., possess very 
different developments of the lateral system. The first represents the 
pediculates ; it shows postorbital and spiracular as a single series, the spira- 
cular from its position, and there appears to be an angular and a jugular 
