418 Scientific Proceedings, Royal Dublin Society. 



On the whole, it seems that this ray for the most part inhabits moderately deep 

 water. The only sheltered bay in which we found it was Downies Bay, where a 

 single large specimen occurred. None of the localities from which it has been recorded 

 on the East coast of Scotland can be so described. The younger immature forms 

 appear to have no special habitat, and may probably be found at any depth or locality 

 inhabited by the mature form. 



(ii.)— DEFINITION OF IMMATUEE FISH. 



The term immature is here used in the same sense as by Dr. "Wemyss Fulton, viz. 

 it is restricted " to young fish which have never developed milt or roe," and which 

 therefore have not become adult. 



To Fulton belongs the credit of being the first to endeavour to arrive at a standard 

 of maturity of other than a purely arbitrary character. It appears to me, however, 

 that his method is open to some slight improvement. As far as I can judge from his 

 tables and remarks his limit is derived from a consideration of the smallest sizes of ripe 

 or nearly ripe fish, without regard to sex.' Now if there is a difference in the sizes at 

 which the sexes arrive at maturity, as indeed appears from Fulton's own remarks, a 

 limit so arrived at must necessarily exclude from its benefits some immature forms of 

 the sex which grows to the largest size before becoming mature. To me it appears 

 preferable to fall into the opposite error, and, by fixing the limit at what appears to be 

 the minimum size of the larger sex, to include among the immature some mature 

 members of the smaller sex. The former method appears to have an especial disad- 

 vantage, since, if the capture of fish so comprised as immature could be prevented, no 

 protection would thereby be afforded to members of the larger sex {i.e. the female in 

 almost all cases) at the very time when they would most appear to need it, viz. when, 

 having safely passed through the manifold dangers of early existence, they are just 

 about to become mature, and are infinitely more likely to survive to reproduce their 

 species than small fish at the mercy of every enemy, a point which is emphasized by 

 Fulton himself. [Vide op. cit., pp. 195, 196). 



With the intention, therefore, of exhibiting the difference between the sizes of the 

 sexes in relation to maturity, I have prepared five tables. 



The first two omit the question of sex, which is dealt with in the third and fourth, 

 whilst the fifth shows the conclusions arrived at, and the difference, if any, between 

 those of Dr. Fulton and myself on our different methods of inquiry. The third 

 column shows the limit fixed at the recent Fishery Conference. This last limit neither 

 has, nor professes to have, any biological significance, and in the case of Turbot 

 and Brill is obviously too small to have much beneficial effect should it ever be acted 

 upon. I have added a few remarks in further evidence on some of the forms dealt with. 

 It will be noticed that I have spoken of fish approaching ripeness in place of nearly 

 ripe fish, as used by Dr. Fulton. By the former term I mean to include such fish as 

 are half ripe or more, since I do not think it probable that a very material elongation 

 takes place during the period which elapses before spawning. 



My conclusions are given in all diffidence, since the materials at my disposal in the 

 case of many species are altogether insufficient. They must be looked on rather as 

 additions to the evidence on this subject so ably set forth by Dr. Fulton. The possible 

 existence of local variation must not be forgotten. 



^ Dr. Fulton has since informed me that the above surmise is correct, and that, as 

 a matter of fact, his smallest specimens were almost always (or perhaps always) males. 



