GOBIES. 
243 
The Scandinavian Gobii may most easily be dis- 
tinguished from the two following genera by the num- 
ber of rays in the first dorsal fin, which in the former, 
as a rule, is not under 6; but the most universal char- 
acter lies in the arrangement of the jaw-teeth in several 
rows, the front row containing the largest teeth. The 
size of the gape and the form of the body, which shows 
strong lateral compression only in the caudal part and 
sometimes only at the extreme end thereof, are with 
these exceptions the most striking characters of the 
true Gobies. The branchiostegal rays are 5 in number, 
the three middle ones being closer to each other at 
the base than to the other two, and the second (the 
next to the lowest) generally marking with its point 
the ano-le at which the branchiostegal membrane turns 
inwards to its union with the isthmus, on about a, level 
with the lower end of the base of the pectoral fin. 
The differences between the sexes have been re- 
marked in particular by Malm" and Heincke In the 
males, which may also be recognised externally by 
their longer and more pointed genital papilla, one or 
more of the anterior rays in the first dorsal fin, and 
the posterior rays in both the second dorsal and 
the anal fins, are, as a rule, elongated. In colour they 
are distinguished by the greater abundance of black 
pigment, especially in the anal and ventral fins, by 
ocellate spots and by stripes of a particular colour on 
the dorsal fins and the sides of the body. But these 
sexual differences vary according to age and size, the 
older and larger females very often resembling the 
males in colour. The coloration is also far from con- 
stant, being deepest, as usual, during the spawning- 
season, and being further subject to sudden changes 
in accordance with the mood of the fish and the colour 
and light of its surroundings. 
Heincke was the first to point out, among the 
chauges of growth, the increase in the number of rays 
in the first dorsal fin — in one species (Gobi us fla- 
vescens ) he found that young specimens had 5 rays in 
this fin, old specimens 6 or (in most cases) 7 or (ex- 
ceptionally) 8. In connexion with this circumstance he 
also points out the individual variations. Out of 208 
specimens of this species which he examined, eight had 
8 rays in the first dorsal fin, three 6, and the rest 7 C . 
The extent of the scaly covering on the anterior 
part of the body also varies with age, as far as this 
can be fixed by the size of the specimen. WintheiG 
and after him Collett 6 and Lilljebokg 7 , believed that 
the most important specific characters within this genus 
were to be found in the differences which the species 
often show in the extent of the naked (scaleless) part 
of the body. In the small species the scales are want- 
ing on the belly, on the body in front of the ventral 
and pectoral fins, and also on a, strip of the back along 
the whole base of the first dorsal fin or the anterior 
part thereof. In the large species of the genus which 
belong to the Scandinavian fauna, on the other hand, 
it is a standing rule that the whole body, with the 
exception of the head, is covered with scales, and some- 
times the occiput and the forehead behind the eyes, 
are also scaly. Heincke has shown that the largest 
Scandinavian species, Gobius niger , during the growth 
of individual specimens passes through stages of de- 
velopment which, with regard to the extent of the 
scales, correspond to the adult state of the smaller 
species. In a specimen 21 mm. in length, he found 
the head, with the occiput and a narrow strip along 
the base of the first dorsal fin, as well as the belly 
between the ventral fins and the vent, entirely bare of 
scales. Of the fry of the same species Lilljeborg 9 
also remarks that “no scales appear on the top of the 
head or on the occiput.” In a male Gobius niger from 
Kanso, in the island-belt of Gothenburg, 67 mm. long, 
the scales are also wanting both on the throat in front 
of the ventral fins and on the part of the dorsal edge 
already referred to. In the same way there are no 
scales in front of the ventral fins in a. Gobius minutus 
50 mm. long, from the island-belt of Stockholm. 
These observations clearly show that neither the 
variable colour of the body, nor the number of rays 
in the first dorsal fin, nor even the extent of the scales 
on the front part of the body may be used as a trust- 
a Skand. Naturf. Mode Kbhvn 1873, Beretn., p. 382. 
b Arch. f. Naturg., 46:ter Jahrg. (1880) Bd. I, pp. 304 etc. 
c According to Canestrini (Arch. Zool. Anat. Fis., Genova 1861, vol. I, fasc., II, p. 12$), the number of rays in the first dorsal fin 
of Gobius guttutus also varies between 6 and 7. 
d Nat.urh. Tidskr., Kbhvn, ser. 3, vol. IX (1874), pp. 197 etc. 
e Christ. Vid. Selsk. Forh. 1874, pp. 153 etc. 
f Sv., Norg. Fisk., I, pp. 563 etc. 
9 L. c., p. 570. 
