TURBOT AND BRILL. 
433 
— though, according to Storer, it attains a length of 
from 12 to 18 dm. — as to remind us very strongly 
of the Megrim. The two others, however, are among 
our better Flatfishes — one of them among the best and 
fattest. They are also characterized by the exception- 
ally deep (short) form of the body, which is relatively 
shorter than in any of the other Flatfishes. The mouth 
is turned up sharply. The eyes are well separated, 
most so among the Scandinavian forms of the sub- 
family, though not nearly so far apart as in some 
members of the preceding genus. 
Few as are the species of this genus, their rela- 
tions to each other, especially in the case of the two 
that belong to the European fauna, are in the highest 
degree interesting. Not only is their geographical range 
so extensive as to admit of the form’s being influenced 
by very dissimilar environments"; but in addition to 
this a large number of intermediate forms are known, 
which can obviously be explained only on the assump- 
tion that they are hybrids * * * 6 . Malm has described one 
of these forms under the name of Rhombus hybridus. 
Both his specimens were females, and most closely 
resembled Both us maximus. The Royal Museum has 
received from Stromstad, through Mr. C. A. Hansson, 
two males, one of which is more like Botlius rhombus. 
Thus it is very difficult to find fixed, constant charac- 
ters for the two species — for many different combina- 
tions may probably be found. However, the forms 
known in Scandinavia may be distinguished as follows: 
I: Number of rays in the anal fin 
at most 50. Least depth of the 
tail less than 20 % of the greatest 
depth of the body. Abdominal 
curve of the lateral line high and 
short, its height being about half 
its length, which is about 3 / 4 of 
the length of the middle caudal 
rays. 
A : Length of the head behind 
the lower eye more than 17 %, 
and of the left maxillary bone 
more than 12 %, of the length 
of the body Botlius maximus. 
B : Postorbital length of the head 
less than 17 ■% and of the 
left maxillary bone less than 
12 %, of the length of the 
body Botlius maximus hybridus. 
II: Number of rays in the anal fin 
more than 50. Least depth of the 
tail more than 20 % of the great- 
est depth of the body. Abdominal 
curve of the lateral line low and 
long, its height being about Vs 
of its length, which is about 
equal to that of the middle cau- 
dal rays. 
A: Postorbital length of the head 
more than 16 /, and the great- 
est depth of the body more 
than 50 /, of the length of 
the body Botlius rhombus hybridus. 
B: Postorbital length of the head 
less than 16 /, and the great- 
est. depth of the body less 
than 50 %, of the length of 
the bodv Botlius rhombus. 
a If we compare, for example, Canestrini’s descriptions of Botlius maximus and Botlius rhombus from the Mediterranean with speci- 
mens of these species from Scandinavian waters, we find that, though the differences are parallel — the former having a larger head, fewer 
rays in the dorsal and anal fins etc. — still the boundaries between the species are entirely different in the Mediterranean and in our fauna. 
6 We are still without the necessary experimental evidence to show that this is the case; and that this is the only operating influence 
is scarcely probable, for these intermediate forms occur in localities, in the Baltic for example, where only one of these species is found in 
its typical form. 
Scandinavian Fishes. 
OO 
