500 Survey of Fishing- Grounds, West Coast of Ireland, 1890—1891. 



A glance at the column showing the proportion borne by the length of the eye 

 to the head shows that the sexual dimorphism in this respect is much less striking 

 than would be inferred from the four large Irish examples, in which the female C 

 has an eye consjiicuously less than any of the three A. lophotos males. In the 

 Plymouth series, though the average size of the eye is certainly greatest in the 

 males, in two (viii. and x.) out of the six large females it is of the same size as in 

 four of the males (i.— iv.), and is actually greater than in one male (vi.). It must 

 therefore be said that sexual dimorphism of this feature is not invariably apparent 

 even in full-grown examples. The condition of the younger examples only further 

 illustrates the variation of the size of the eye, or of its differentiation in relation 

 to sex, wliich we have already noticed in similar stages from other localities. It 

 is not certain that any of the small Plymouth exam23les are sexually mature, but 

 specimen xviii. is at least approaching that condition. With regard to the length 

 of the maxilla the Plymouth series again greatly reduces the sexual difference 

 apparent from tlie examination of the few large Irish examples, though the average 

 larger size of this structure in the female is maintained. The condition of the 

 younger examples so far coincides with tliat of the small Irish and Norwegian 

 specimens as to indicate that the jaw is usually largest in the female at a compa- 

 ratively early age. 



In dealing with the larger Irish examples {A—D) it was noted that the profile 

 was blunter in the males than in the female. The same conclusion is borne out 

 by examination of the twelve males and six females from Plymouth, but in a 

 modified degree. The profile is more abrupt and blunter in some males than in 

 any females ; but the sex of several examples cannot be distinguished by this 

 character. The small examples, male and female, are indistinguishable from each 

 other in shape, and are more fusiform in appearance than the largest A. lophotes 

 males, and some of the largest females. They agree, however, with the smaller 

 of the large females, and with some of the smaller A. lophotes males. Since the 

 same is the case with the smaller Irish examples, it may be taken that the profile 

 becomes blunter with age, especially in the male. 



The black spot on the ocular j^elvic, noted in the Irish males, is present, or at 

 least indicated, in the Plymouth males, but cannot be detected in the females. 



The variation in the elongation of the anterior dorsal rays is shown by the 

 following figures : — 



