418 ME. B. W. L. HOLT — STUDIES IN [May 1 , 



or arrangement from those of the Common Ling, but the large 

 teeth of the inner row of the mandible and of the vomer, which 

 exhibit the lateral compression and spatulation of the points most 

 strongly, are fewer in number by comparison with Common Ling 

 of the same size ; this is due, no doubt, to the latter being con- 

 siderably younger than the examples before us. The tongue is 

 broad and free, with a sharp anterior edge. There are about 80 

 pores in the lateral line. 



Colours. — The dorsal region of the head and body is a brownish 

 slate colour, shading ventral ly into a brownish grey on the sides, 

 which have a cupreous lustre in very fresh examples, and becoming 

 nearly white in several examples in the ventral abdominal region. 

 The jaws and under surface of the head brownish grey, the branchi- 

 ostegal membrane not darker than the surrounding region, but 

 the tip of the lower jaw and barbel dark. A dark spot on the 

 axilla ; the pectoral dark slate-grey ; the pelvic pale, but speckled 

 with dark pigment. The dorsals slate-grey, both fins darkest in 

 the submarginal region, especially the posterior part of the second 

 dorsal ; the extreme margin light, nearly white in some examples. 

 The anal resembling the second dorsal, but fading into a pale 

 slate colour anteriorly. All these fins have a bluish lustre on 

 their darker parts. The mucous membrane of the mouth may be 

 almost colourless, but is usually rather profusely speckled with black 

 pigment. I am told that it is sometimes black, but have not 

 seen any specimen to which such description would apply. The 

 peritoneum of the body-cavity dark grey or black. 



The Birkelange thus differs conspicuously enough from Ling 

 taken from the comparatively shallow water in our own seas ; but 

 comparing it with Faroe specimens of that species, I find that the 

 principal difference (so far as concerns external pigmentation) 

 that can be affirmed is that the commoner form is rather the paler 

 of the two. We know from Lilljeborg ' that the two species 

 resemble each other in being more vividly coloured in the young 

 condition than when adult. 



In order to emphasize the external differences of the two species I 

 have appended a figure of both. The Ling (Plate XX VITI . tig. 2 ) i> 

 actually some ten inches shorter than the Birkelange (fig. 1), and, the 

 figures being drawn to such scales as to be practically of the same 

 size, the difference in the size of the eyes is not so marked as it 

 would be had examples of the same actual length been represented, 

 since the size of the eye varies in inverse ratio to that of the 

 individual. Nevertheless the eye is seen to be largest in the 

 Birkelange, and its relatively greater length as compared with 

 that of the head is still more conspicuous. Such dimensions ;i> 

 the height of the body and of the caudal peduncle in relation to 

 the total length are practically constant during the interval of size 

 which separates the two specimens, and consequently the value of 

 the figures for purposes of comparison is not thereby impaired. 



1 This author (op. cif. hi. Append, p. 787) describes the coloration of an 

 example of M. abysaorwm 00 cm. long. 



