GRAYLINGS. 
883 
Aver a g e. 
Salmon. 
Grayling. 
Gwvniad. 
Length of the maxillaries _ in % of the length of the head 
39 
31 
27 
,, - „ „ „ „ ., ., „ reduced 
59 
42 
37 
n ?? t, lower juw — — ?? n n n ?? 5 ? n head 
59 
52 
42 
„ ., .. „ - „ •, •• „ „ „ reduced 
90 
60 
56 
Interorbital breadth of the forehead ... „ „ „ „ „ ,, „ „ „ 
47 
44 
41 
The Graylings’ closest approach to the Salmons appears in the following relations: 
Average. 
Gwyniad. 
Salmon. 
Grayling. 
Number of rays in the anal fin 
15 
11 
12 
Base of the anal fin in % of the length of the body 
11 
8 
9 
Distance between the adipose fin and the caudal fin ,, ,, „ ., ,, ., „ ., 
9 
11 
11 
» „ » anal ,, „ „ „ „ - „ „ „ „ 
9 
12 
11 
To the Gwy niacls the Graylings come nearest in the following relations: 
A v e r 
g e. 
Salmon. 
Gwyniad. 
Grayling. 
Postabdominal 
length 
in % of the 
length of the body 
20 
25 
26 
Height of the 
dorsal fin 
11 ?? 11 11 
13 
15 
15 
Length of the 
ventral fins 
11 11 11 11 
12 
14 
14 
n n 
middle caudal rays 
11 11 11 11 
7 
5 
5 
n n n 
suboperculum 
'll 11 11 11 
„ „ „ head 
25 
29 
29 
11 11 . 5 ? 
head reduced 

- 11 11 11 11 
11 11 11 11 
67 
74 
73 
In the size and texture of the scales the Graylings 
also stand nearer to the Gwyniads, and partake, to- 
gether with the latter genus, in the approximation of 
the Sal monoid type to the Cyprinoid. 
The development of the dorsal tin in the Gray- 
lings, their most distinctive character, has the result 
that the average distance between this tin and the 
snout is only about 35 % of the length of the body. 
In this respect Thymallus stands alone in the Sal- 
monoid family. The opposite extreme we find in Mal- 
lotus, where the said average is more than 50 % of 
the length of the body. 
The name of Thymallus (Gv/uaA/.og) dates from 
.Elian — about 120 A. D. — and has reference to the 
thymy smell which some have supposed the fish to 
emit. In Linnaeus it was a specific name; Cuvier 
raised it to a generic rank". 
Excluding the two nominal species Tliym. ontari- 
ensis and Tliym. Mertensii, which have been recognised 
by Valenciennes * 6 alone, and which have already been 
repudiated by Gunther*, and also excluding the ob- 
scure Tliym. Grubei, Dye. and Tliym. brevirostris, Ivessl. 
from Southern Siberia and Central Asia, there hardly 
remain more than two species of the genus Thymallus 
that can lay claim to recognition. Of these two the 
North Siberian Tliym. arcticus ( Pallasii) d is especially 
remarkable as representing in by far the most respects 
the characters of youth and of the females, while in 
others — even in the most distinctive character of the 
genus, the length of the base of the dorsal fin — it 
has attained a more advanced development than our 
common species, 
a Regne Animal , ed. 2, tome 2, p. 306. 
6 Cuv., Val., Hist. Nat. Poiss., vol. XXI, pp. 452 and 453. 
c Cat. Brit. Mus., Fish., vol. VI, p. 200. 
d Thymallus signifer , Richardson, from North America, is probably identical with this species, though for the present we must leave 
this question open. See Smitt, Riksm. Salmon., p. 206. 
