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Part III. — Twenty-fourth Annual Report 



The Caudal Fin of luscus has its hind margin slightly concave, that 

 of minutus is distinctly concave, and in esmarkii the hind margin is 

 deeply cleft. 



The ventral fin ends in a filamentous tip in all three species. 



TJie Mandible projects a little in front of the upper jaw in esmarkii ; 

 in minutus and luscus the upper jaw projects in front of the lower. 



The side and tip of the lower jaw are dark coloured in esmarkii. The 

 under-surface of the dentary part of the lower jaw is white in luscus; pale, 

 colourless in minutus. In consequence, the sensory pits on the under- 

 surface of the dentary show up well in luscus and are faint in minutus. 



The Barbel is long and stout in luscus and minutus. In esmarkii it is 

 thin and short, not being longer than half the diameter of the eye. In 

 the last species the barbel often lies back along the under surface of the 

 lower jaw in the hollow between the two dentaries. The barbel is not 

 so short in esmarkii as it is in Gadus virens, in which species it is very 

 inconspicuous. 



The Lateral Line is curved over the abdomen in all three species. In 

 luscus and esmarkii the line is dark and more prominent than in minutus. 

 The bend rises from the hind straight portion more abruptly in luscus ; in 

 minutus and esmarkii the rise is more gradual. 



The Ames is beneath the beginning of the first dorsal fin in luscus, and 

 beneath the second half of the corresponding fin in minutus and esmarkii. 



The Eye in the three species here discussed is specially large. In 

 luscus it is slightly smaller than in minutus and esmarkii. The diameter 

 of the eye is equal to or greater than the length of the snout, i.e., the 

 distance from the tip of the upper jaw to the anterior edge of the orbit. 

 They all exhibit at times the loose cornea which is sometimes inflated 

 with gas or fluid, giving the eye the well-known bulged appearance. 

 Sometimes cysts are found on the front of the eyeball in the region of 

 the iris. 



Two of the larger esmarkii, measuring 18 -5cm. and 19cm. in length, 

 had eyes which appeared to be larger in proportion than the smaller fishes. 

 The eyes measured in horizontal diameter 7*3 and 7*8 per cent, of the 

 total length of the fish respectively. Four others measuring 19cm., and 

 one of 21cm., had eyes measuring 7 per cent, of the total length of 

 the fish. The small difference in diameter will, of course, entail a con- 

 siderable difference in the area of the eye, and it is by the area, not the 

 diameter, that the eye of the observer makes the comparison. Any 

 variation towards an increase in the size of an already specially large 

 character will of necessity attract attention. 



The barbel in luscus is rather bigger and stouter than that of minutus. 

 In five specimens of the latter the barbel measured two-thirds or a little 

 more than the horizontal diameter of the orbit. 



In the key are introduced the following Gadid species — G. callarias, 

 G. virens, G. pollachius, G. luscus, G. minutus, and G' esmarkii. 



KEY. 



I. Lower Jaw (Length of) — 



a. projects in tront of Upper Jaw, . . virens ; pollachius ; esmarkii. 



b. of same length as ,, . virens (young) ; mimitus (sometimes). 



c. shorter than ,, . . callarias; luscus; minutus. 



II. Anus (Position of)— 



a. below the beginning of the First Dorsal Fin, . . . luscus. 



b. ,, ,, first half ,, ,, ,, . pollachius ; minutus. 



c. ,, ,, second ,, ,, ,, „ minutus; virens; esmarkii. 



d. „ „ first half ,, ,, Second ,, „ . . callarias. 



