of the Fishery Board for Scotland. 135 
The teeth of the outer series in the upper jaw are a little larger than 
the inner ones. 
The snout is almost equal to the length of the diameter of the eye. 
[This character is preferably expressed as follows :—The diameter of the 
eye is equal to or exceeds the length of the snout. | 
The eye is very large, being a little less than one-third of the length of 
the head. 
The barbel is slender, being about half as long as the eye. 
The fin-formulz were—1 D, 15-16; 2 D, 23-25; 3 D, 22-25; 1 A, 
27-29; 2 A, 23-25. 
In the “Scandinavian Fishes” the fin-formule are given as follows :— 
1 D, 14-16; 2D, 22-26; 3D, 22-27; 1A, 26-30; 2A, 24-38. 
Pect., 19. Ventr., 6. Vertebree, 52. 
Attention is called in the latter work to the lateral line which is “ dark 
(though not very distinct) and anteriorly slightiy curved.” 
The numbers of fin-rays and vertebre found in the esmarkit examined 
for the purpose of this research are set out in Table III., p, 145. 
Giinther drew attention to the cysts that are found in the eye of 
esmarkii. They are arranged in the iris, may be few in number, or they 
may occupy almost the whole of the iris, in this way appearing as a ring 
of white balls. These cysts occur in minutus also. 
In 1893 Professor M‘Intosh described a ‘“‘peculiar Poor Cod” which 
is, he informs me, a Gadus esmarkit. Professor M‘Intosh has kindly 
permitted me to have a drawing made of this specimen, and it is 
reproduced in pl. ix. 
Since then Dr. Fulton has obtained it in large numbers, Schmidt has 
described in detail the post-larval and young stages of G. esmarktt up to 
a length of 5:4cm. He remarks that in an example of 19mm. the eyes 
are but relatively small, their diameter being of the same size or but little 
larger than the distance from their anterior margin to the end of the 
snout. 
A Specific Description. 
For the purpose of determining the specific description a large number 
of measurements was made on specimens of each species. These show 
that external measurements made on a single fish may be of little value 
from the point of view of specific diagnosis, since the variation of each 
character is large, and, so far as is apparent, independent of, or at least 
not necessarily correlated with, any other contiguous character. The 
amount of variation which may occur in the characters, while the general 
specific identity is retained, is large. Specific identity means identity of 
function. The specific characters mean a difference in the life and habits 
of the animal which we may not be able at present to estimate. The 
correlation between the specific characters and the life of the fish is a 
field hitherto practically unexplored. Thus there are perplexing simi- 
larities and differences between fishes. The former mean that the fishes 
perform similar functions, but at the same time in certain other functions 
they occupy different spheres in the economy of the sea. 
In working out the specific characters it is well to consider the points 
in which the species agree, in order that these may form part of the 
generic or sub-generic description. The object of the specific description 
is to enable an observer to diagnose a single fish, and for that purpose a 
chart is required. 
The Genus may be divided into certain sub-genera. The species may 
be arranged into two or more groups, each characterised by some common 
character. The species in each sub-genus may then be distinguished 
