560 
SCANDINAVIAN FISHES. 
irregular rows, the outermost row containing the largest 
teeth both in the upper jaw and the lower. A similar 
card of teeth, set across the palate and curved, occupies 
the head of the vomer. The upper pharyngeals on each 
side form two disks, crowded with fine, rather blunt 
teeth. The anterior disk is narrow and of uniform 
breadth, the posterior (on the two hind pharyngeals, 
which are coalescent) large and quadrangular with 
rounded corners or crescent-shaped. The cards of teeth 
on the lower pharyngeals are oblong. The four bran- 
chial arches are furnished with short, spiny protuber- 
ances instead of gill-rakers. The gill-openings are j 
large. The branchiostegal membrane is moderately in- 
cised underneath, with a narrow, free, dermal margin 
across the isthmus. The whole head is clothed with a i 
I 
thick, mobile skin, loosely attached to the body, and ! 
entirely covering and concealing the opercular bones. 
In structure the scales of the Tadpole Fish very 
closely resemble those of the preceding genus. They are 
furnished exclusively with concentric, denticulated striae 
(ridges). On the other hand, the nucleus is usually 
very large — though sometimes reduced in the extreme 
— and only the younger (smaller) scales have continuous 
striae, following the elliptical or oblong outlines of the 
scale. In other cases they are more or less interrupted 
at both ends of the scale, in the anterior (inserted) 
part to leave room for a longitudinal, smooth patch at 
the middle, as a continuation of the nucleus, and in 
the posterior (free) part of the most developed scales 
to correspond to the configuration of the truncate mar- 
gin of the scale. This margin is furnished with a 
greater or less number of teeth — Kroyer has counted 
as many as 18 — and here the said stria? partly run 
straight out to the margin, and partly scatter into small, 
irregular, vermiform, transverse stria?. We must re- 
member, however, that these ciliate teeth at the hind 
margin of the scales are often wanting: in some speci- 
mens we have failed to discover any of these ciliated, 
truncate scales, while in others they apparently occur 
only on the hind part of the body. The scales on that 
part of the body which lies behind the vent, are also 
more regularly arranged and flat, but on the forepart 
of the body as well as on the head they are more 
irregular, rather more depressed, and as it were concave. 
During life the fish is coated with a thick layer of 
slime, which entirely conceals the scales, and renders 
the whole surface of the skin smooth and shiny. The 
lateral line, which is only slightly marked, and forms 
a small curve in front, is hardly distinguishable during 
the life of the fish, but in specimens that have long- 
been preserved in spirits, this curve appears as a row 
of light-coloured protuberances". 
The vent is large and thick-lipped, with an anal 
papilla behind it, and is situated just in front of the 
beginning of the anal bn. 
The pectoral fins are fairly large, their length being 
about 1 5 — 17 % of that of the body, and are rounded 
at the tip. Their basal part is somewhat elongated 
(brachiate), and their rays, of which the middle ones 
are longest, are thick at the base and at the tip very 
regularly divided into 8 branches, running parallel to 
each other. 
The ventral fins are set farther forward than the 
pectoral, at a distance from the beginning of the anal 
fin of about 1 8 1 / 2 — 22 % of the length of the body. 
They contain 6 rays, the first two being much longer 
than the others and furnished with long, free, fila- 
mentous tips, arched in a forward direction. The se- 
cond ray is the longest, sometimes measuring as much 
as 1 8 1 / 2 % of the length of the body. The four inner 
rays are small, closely united, and branched, but with 
the tips themselves as it were coalescent. 
The first dorsal fin, which begins at a distance 
from the tip of the snout measuring in young speci- 
mens 26 — 28 %, in old 29 — 33 %, of the length of the 
body, is only rudimentary. It is set in a deep groove 
formed by the dorsal edge, and is composed of one 
large, distinct, simple ray, which is, however, short, its 
length being always less than the longitudinal diameter 
of the eye, and behind which we find two extremely 
small and indistinct rays. The latter rays can often 
be distinguished only with the help of scalpel and mag- 
nifying-glass. The second dorsal fin begins just behind 
the perpendicular from the base of the pectoral fins, 
at a distance from the tip of the snout of about 31 — 
36 % of the length of the body. It is of almost uni- 
form height, and runs along the back for a distance 
equal to about 49 — 54 % of the length of the body, 
to the very base of the caudal fin, the space between 
these fins being extremely small or hardly perceptible. 
a “Above the pectoral fins, on each side, was a row of tubercles from which commenced the lateral line, which was (midway) in- 
curvated”: Pennant, 1. c. 
h In our largest specimen 14. 
