FATHER-LASHER 
189 
fish expands the gill-covers, an operation usually accom- 
panied by a grating noise", and resorted to by the fish 
as soon as it is drawn out of the water, these long spi- 
nes point upwards and outwards, in a way which gives 
them some resemblance to a pair of horns. From this 
circumstance has arisen the name of Ox-simpa (babalis). 
Besides the long spine, a third part of which generally 
projects out of the surrounding skin, the margin of the 
preoperculum is furnished with three smaller spines, 
which vary in form, but seem to be always present: 
the lowest of them is turned downwards and forwards. 
The suboperculum is furnished with two or three 
pointed spines. Another character which distinguishes this 
species, is the circumstance that, from the margin of 
the skin which is united to the upper part of the eye, 
and which resembles an eyelid, there hang down over 
the margin of the iris five or six small, thin, dermal 
filaments, the next to the last being twice as long as 
the others and, during life, erected vertically upwards 6 . 
A similar, though much longer, dermal filament — or 
sometimes two — appears at the truncate end of the upper 
jaw-bone 6 . The branchiostegal membrane is interiorly 
united to the isthmus, without a free fold across the 
latter. The course of the lateral line is fairly straight 
and forms no curve in its posterior part. It is gene- 
rally armed with stiff points, which are anteriorly set 
in large numbers on the small, slightly raised, scaly 
disks which form the line, but gradually diminish in 
number posteriorly and, as a rule, completely disappear 
at the end of the second dorsal fink The scattered, 
pointed, scaly plates with which the sides of the Sea 
Scorpion are furnished, are entirely wanting in this spe- 
cies in its adult state; but it passes through a larval 
stage, so to speak, during which it has pointed, scaly 
spines on the anterior part of the body, both above and 
below the lateral line. These spines have disappeared, 
however, when the fish has attained a length of 26 
mm.' 6 , and the somewhat granulated skin is subsequently 
quite unarmed and covered with a clear, thick mucus. 
The two dorsal fins are quite distinct, but often only 
imperfectly separated from each other. The membrane 
of the anterior fin is often united to the base of the 
first ray in the second, higher up in some specimens 
than in others. In the first dorsal fin there are gene- 
rally 8 rays, but sometimes only 7, the two first being 
usually closely joined at the base; in the second from 
10 to 12 and sometimes 13. The anal fin contains 8 
or 9 rays and sometimes 10. The pectoral fins, in 
which there are 14 or 15 rays, are completely without 
the serrate ridges which appear on the inside of the 
rays in the Sea Scorpion. This is also the case with 
the ventral fins, which have one, short, spinous ray, 
hidden by the skin, and three simple, articulated rays, 
the middle one being the longest. The caudal fin con- 
tains from 12 to 14 rays, from 7 to 9 of the middle 
ones being branched at the tip. 
In external form the difference between the sexes 
is less striking in this species than in the preceding 
one. The male may be recognised, however, by the 
more slender body, the larger spines on the head and 
the elevation of the anal region into a long, conical 
papilla. As usual, however, its chief external distinction 
lies in the greater length of the fins, especially of the 
ventral, which in this sex, at least when the fish is 
over 60 mm. in length, apparently vary between 16 
and 20 % of the length of the body, and in ordinary 
cases extend as far back as the vent or even farther. 
The base of the anal fin, too, is generally longer in the 
male, but the distance between the insertion of the 
ventral fins and the beginning of the anal fin is less 
in the male than in the female, a circumstance which 
gives us the general rule that, in the male the base 
of the anal fin is at least 80 % of this distance, in the 
female at most 76 %. Further, in those respects in which 
distinct changes of growth appear, the male represents, 
in this species also, the lowest stages of development, 
e. g. in the size of the eyes (see the table below). 
The difference between the sexes is more apparent 
if we observe the coloration, though it is extremely 
variable. Our plate gives the colouring of both sexes 
as it usually appears (the originals are from the Baltic). 
The prevalent green colour is a distinguishing mark 
a According to Sorensen (Om Lyclorganer Jios Fislce. Kbhvn 1884, p. 79) this sound originates at the articulation of the preoperculum 
with the byomandibular bone. According to Dufosse (Ann. Sc. nat., ser. 5, Tome XIX et XX — 1874), we may conclude that the vibration in 
the articulation, which is the immediate cause of the sound, is due to the vibration of the muscles of the hyomandibular apparatus which in these 
muscles, as in all others, accompanies their strongest possible contraction. This sound also occurs, though there it is weaker, in the preceding species. 
b Cf. above, on (Jentridermichthys hamatus. 
c In a specimen 71 mm. in length from Waideguba (Kola Peninsula) the lateral line is without any spine whatever, except the stiff 
margin of the middle pores, which is raised in a posterior direction. 
d Cf. Malm and Collett. 
