of the Fishery Board for Scotland. 127 
In the second anal lusews and minutus are again in close agreement 
with averages of 21 and 22 respectively, while esmariii shows an average 
of 27 rays. 
Esmarktvi has a much larger number of fin-rays than either /uscus 
or minutus. 
The average number of fin-rays in all three dorsals is, for /useus 56 ; 
minutus, 57; and esmarkii, 66. 
It was {noticed above that the extent of the dorsal edge which bore 
fin-rays was the same in all three species. It therefore follows that in 
esmarkit we have to deal with a rather lighter and less robust ray than in 
the two others. 
The anal rays (first and second) amount to 55 in the case of Juscus, 50 
in minutus, and 56 in esmarkiit, Here luscus has a total of 55 rays 
distributed on a portion of the ventral edge equal to 50 per cent. of the 
length of the fish, while mnwtus has 50 rays on 46 per cent, of the 
length, and esmarkii has 56 rays ona part equal to 45 per cent. of the 
length of the fish, In the anal fin-bearing part we have in esmarkit a 
greater number of rays to the unit of length than in duscus and minutus. 
If, now, we divide the average length of the fin-base by the average 
number of rays we shall get a relative index of the robustness of the fin- 
rays in the different species, and in the different fins of the same species. 
Average Index of Fin-rays for each Fin. 
Species. hn sh ete 3D. ii Da. 
G. luscus, A 8 EOF ‘65 ory fa 
G. minutus, ved 84 1:04 Hl Pek | 
G. esmarkia, a St =| 88 63 ‘96 63 
| 
The index of the fin-ray of esmarkii is smaller than those of luscus 
and minutus, in all the fins except the first. There is also to be noticed 
that in each species the indices of the third dorsal and second anal agree 
closely, and together differ from the indices of the second dorsal and first 
anal fins. In the two former fins the rays are set more closely together, 
which probably means that they are less robust rays than those of the 
other fins. 
The three species agree fairly closely in their respective indices for the 
first dorsal fin. In all three species the indices for this fin are less than 
those of the second dorsal and first anal fins. 
From the Tables given above it is seen that there is no typical generic 
number of rays either for the dorsal or anal group, In the two closely 
related forms, /uscus and minutus, there is an almost identical number of 
fin-rays for each fin in the dorsal group, but they are both widely 
separated from esmarkii in this comparison. In the matter of the anal 
fin-rays, Juscus aud minutus were separated. Here the anal rays have a 
specific value. The dorsal fins are together, on the other hand, a sub- 
generic character. The extent of the dorsal edge of the body furnished 
with fin-rays is the same in all three species; but the quality of the rays 
is specific, and involves different numbers, 
