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



of old parents pass through the various " smolt " and " grilse " stages, and finally 

 resemble their parents in every respect. 



If, as we are entitled to assume, the attainment of a large size is for the 

 advantage of the species, it is obvious that that advantage would accrue from the 

 development of any character which would induce the largest fish to mate with 

 each other ; such a character is presumably furnished in the case of large S. leven- 

 ensis by the peculiar pigmentation of the adult, and it is possible that the more 

 pronounced characters (in this case sexually dimorphic) of the scaldfish may be 

 interpreted in the same way. It so happens, however, that Sir J. Maitland finds 

 that the size of the male parent is of no apparent importance in trout, and that 

 the size of the offspring depends on the size of the eg^, which, in turn, is in pro- 

 portion to the size of the parent female.* Such being the case, the object of the 

 accessory sexual characters of the male t^caldfish is not apparent, if we were not 

 aware that there is a mechanical difficulty in the fertilization of the ova of young 

 females by the spermatozoa of old males, which Sir J. Maitland informs us is the 

 case. From this it is evident that an old male can only reproduce its species by 

 union with a mate of corresponding size, and possibly the elongated rays of the old 

 male scaldfish may assist in securing this object. In any case it seems quite 

 reasonable to suppose that, as in the case of the Lochleven trout, the offspring of 

 young or small scaldfish may never attain the characters of the full-grown fish, so 

 that within the limits of one species there may be two well-marked forms — one 

 attaining a large size, and becoming sexually dimorphic, while the other remains 

 permanently stunted and practically indisting-uishable as to sex by external 

 characters. 



It may be fm-ther conjectured that the elongation of the rays in old males is 

 not merely, as it were, ornamental, but of actual service in the discharge of the 

 sexual function. Little is, or is likely to be, known of the breeding habits of sea 

 fish, but it is quite possible that there may be some sort of conjugation in which 

 the elongated rays may play an important part as organs of prehension. 



A Mediterranean scaldfish, A. conspersus, Canestr., is considered by Professor 

 Smitt to be identical with A. laterna. On this matter we have no opportunity of 

 offering an independent opinion. In discussing the species, Smitt makes no 

 mention of Mr. Cunningham's Paper, either in the list of references or in the 

 text. This might be taken as a rather forcible method of indicating dissent from 

 the views therein expressed, were it not that the author, though he has chosen to 

 publish in English, shows no signs of having attempted to make himself acquainted 

 with the observations of recent British writers. 



* A fact vtich probably holds good for sea-fishes, and accounts for the discrepancies in statements by 

 different writers as to the dimensions of the ovum of a species. 



