76 
SCANDINAVIAN FISHES. 
the base of these tins and there become united into large 
‘Uncovers’, though still maintaining their oblong, linear 
form.” In this idea of the progression of development 
(metamorphosis) between the two genera, we may also 
find the explanation of the other differences between 
them. In Pterycombus the dorsal and anal fins are 
longer and begin nearer the head, but this is also true 
of the adult specimens of Brama compared with the 
younger. In the former genus the superior profile of 
the body slopes uniformly in a slight curve from the 
beginning of the dorsal fin to the tip of the snout, 
and this is also true of the younger specimens of Brama , 
in which genus the height of the forehead and the abrupt 
slope of the snout become developed only later in life. 
The spines on the scales which Ave have seen in Pte- 
rycombus, are also represented in Brama, but are here 
really to be regarded as evanescent growths. In other 
respects the formation of the scales is essentially the 
same in both genera; but the Avidening of the high 
scales and their singular form, reminiscences of the 
Ganoid type, are more marked in Pterycombus and the 
younger specimens of Brama. Thus in the develop- 
ment of the dorsal and anal fins Pterycombus is more 
advanced than Brama, AAdiile in the other characters 
mentioned above Pterycombus has stopped short at a 
stage of development corresponding to the juvenile stage 
in Brama. As in Pterycombus, the ventral fins are 
also covered Avith scales in this genus, and in Brama 
there also appears a i'oav of singular scaly growths, 
elongated into a spoon-shaped form, and situated in 
the axil on a dermal flap Avhich extends along the 
inner base of the pectoral fin". The gill-openings are 
also large in Brama, but the branchiostegal membranes 
are united under the isthmus from about the middle 
of the loAver jaAv. 
In the genus Brama 9 species have been distin- 
guished among adult specimens, but the correctness of 
perhaps most of them is still doubtful. In his meri- 
torious treatment of this question Lutken b has pointed 
out the character Avhich may be derived from the dif- 
ferent number of rays in the anal fin. When we also 
observe that the species, all West Indian, Avhich are 
distinguished by the shortest anal fin, also have the 
hind margin of the caudal more or less curved in an 
S-shape, Avhile in the other species it is simple but 
deeply forked, Ave have here a ground for the distinc- 
tion of at least two groups of forms Avithin the genus. 
This, hoAvever, does not preclude the possibility that 
even the number of rays and the length of the anal 
fin may also prove subject to such changes due to age 
that the character derived therefrom may lose its 
validity. HoAvever, as the same changes affect the dor- 
sal fin as Avell, Ave naturally obtain a surer test of the 
character by comparing the tAvo fins Avith each other. 
Even the number of rows of scales on the body may 
be employed, at any rate in extreme cases, as charac- 
ters for the species. But here Ave are met by the dif- 
ficulty of counting these roAvs Avith uniformity and 
excluding the more or less irregular layers of scales 
iu front of the caudal fin and on its base. Lutken 
remarks that if, Avith Gunther, Ave count along the 
lateral line, Ave find from 80 to 95 i’oavs, but according 
to Lunel’s method of counting in a straight line from 
the upper end of the gill-opening, Ave find only from 
70 to 76 roAvs in Brama Bail, the species in Avhich 
Lilljeborg has counted from 70 to 80 roAvs. The 
statements Avhich are not accompanied by a clear ex- 
planation of the manner of counting, thus lose a great 
part of their value, especially as age seems also to 
involve an increase in the number of roAvs of scales. 
Among the forms of this genus two Scandinavian 
species have been distinguished, both Avith the base of 
the anal fin more than 70 % of that of the dorsal: 
1: Base of the anal fin more than 40 % of 
the length of the body; greatest height of 
the dorsal about -j 3 of the length of the 
head ___ - Br. Kaii. 
2 : Base of the anal fin less than 40 % of 
the length of the body; greatest height 
of the dorsal almost equal to the length 
of the head - Br. longipinnis. 
For the morphological significance of this dermal flap see below on Cliirolophis galerita. 
Spolia Atl., 1. c., p. 497. 
