FLOUNDER-FISHES. 
369 
Almost the same remarks apply to the system of 
the lateral line. As a rule it is well-developed, though 
sometimes externally indistinct. In all the Scandinavian 
species its extent is normal, though a portion of it on 
the head, is sometimes reduced by the removal of the 
eye. Thus, in the Turbot all those branches of the 
system that appear in a Codfish for example, are re- 
peated, as appears from a, comparison between fig. 104 
and fig. 105. From the temporal region on each side 
of the body an occipital (supratemporal, spt) branch 
runs up towards the dorsal edge. In the Flounders 
this branch runs to each side of the dorsal fin and 
coasts it in a forward direction to the beginning of the 
fin, or ramifies, in which case it may follow the base 
Fig. 106. Cephalic system of the lateral line on the eye side of a 
Plaice. After Tkaquaib. sptr , dorsal branch of the lateral line. For 
the signification of the rest of the letters see the preceding figure. 
of the dorsal fin both forward and back (fig. 106). 
Down from the temporal region runs the mandibular 
branch (m), along the hind margin of the preoperculum 
and on the under surface of the lower jaw. In a for- 
ward direction the frontorostral branch (fr) crosses the 
frontal and ethmoid bones to the turbinate bones, with 
a connecting branch (c) between or behind the eyes, 
from the branch on one side of the body to that on 
the other. Each frontorostral branch sends out a sub- 
orbital branch (so) behind the eye. In the Plaice (figs. 
106 and 107) the frontorostral branch of the blind side 
disappears behind the orbital region; but the connecting 
branch is persistent, being externally visible on the eye 
side, and at the hind margin of the upper (transferred) 
eye passes straight through the head to the remainder 
of the frontorostral branch of the blind side. In several 
exotic genera the lateral line of the body is doubled 
or even trebled, partly, as we have mentioned above, 
by a dorsal branch coasting the base of the dorsal fin, 
and partly by a ventral branch along the base of the 
anal fin. In these cases it may happen either that both 
sides of the body are alike in this respect, or that the 
eye side is furnished with two or three lateral lines 
and the blind side with one or none. 
All the fin-rays are soft (articulated), sometimes 
simple and sometimes branched. Sometimes they are 
simple in all the fins, sometimes branched in the caudal 
fin alone, sometimes in the paired fins as well, and 
Fig. 107. Corresponding figure of the blind side of the head in the 
same fish. After Tkaquair. For the signification of the letters see 
the preceding figure. 
sometimes branched in all the fins. The pectoral fins 
are usually set fairly high, and the ventral fins in front 
of, or sometimes exactly in, the perpendicular dropped 
from the insertion of the former fins. These paired 
fins, however, are very often reduced, as we have men- 
tioned above; and the ventral fins may be sometimes 
united by the fin-membrane to the anal fin. In this 
case, when only one of the ventral fins (that of the 
eye side) is developed, it presents the external appear- 
ance of an anterior lobe of the anal fin. 
At the beginning of the latter fin, just behind the 
vent, there sometimes projects a strong spine. This is 
the lower end of the first interhannal spine of the anal 
fin, which spine is also called the postabdominal bone. 
Scandinavian Fishes. 
47 
