198 Part III — Sixteenth Annual Report 



this, and also because of their nutritive qualities, they form one of the 

 most important constituents of fish-food existing in the sea ; this remark 

 applies, of course, to young Entomostracans as well as to the other 

 orders of this great class of invertebrata. The minute nauplei, the larger 

 megalops, and other stages of crustacean growth, along with embryo 

 mollusca, form, no doubt, the principal food of young fishes of all kinds. 

 Mr H. Dannevig, in his paper" 55 " describing his experiments in the rearing 

 of larval and post-larval plaice and other flat fishes, gives some interest- 

 ing observations bearing on the value of young Crustacea as fish food. 

 The examination of the stomach of large numbers of young fishes at the 

 Marine Laboratory of the Fishery Board for Scotland at Tarbert, Loch 

 Fyne, during 1886-87, some of the results of which are published in 

 the Board's Fifth Annual Report, also show that the importance of 

 young Crustacea as fish food has long been recognised, and, as a matter of 

 fact, their importance in this respect cannot well be overstated. It is 

 evident, therefore, that the study of the distribution of these miniature 

 forms, and of the influences that govern their increase or decrease, as 

 well as the investigation of their life-histories and development, are well 

 within the scope of scientific fishery work. 



The records of miniature Crustacea included in the lists of tow-net fauna 

 that form the basis of this paper refer chiefly to the young of various 

 species of the Decapoda. Among the more common of the larval 

 Decapoda included in the tow-net gatherings are those of Portunus (or 

 swimming crabs), of Porcellana longicornis, of the Eupaguridae (or soldier 

 or hermit crabs), and of Nephrops norvegicus (the "Norway lobster"). 

 The young of Galathea (or what some fishermen call the " bastard 

 lobster ") and of various shrimps, such as Crangon and Pandalus, which 

 are at times more or less frequent, are also included among these records 

 under the general name of young or larval Crustacea. Young Schizopoda, 

 as such, are specially referred to in the lists only when they happen to be 

 common or abundant ; at other times they are included with the young- 

 Decapods. The larvaa and young of the Barnacle are more frequently 

 recorded separately, but they also are sometimes included with the others, 

 and the table of distribution comprises the records of all the three 

 groups. The total number of records referring to young and larval 

 Crustacea is about three hundred and forty, and an enumeration of them 

 is contained in the annexed Table. This Table shows that in some 

 respects the distribution of the immature Crustacea is somewhat similar 

 to that of the Coelenterata. If, for example, the total number of records 

 of immature Crustacea for each of the three inner stations be compared 

 with those for the three outer stations, they will be found on an average 

 larger than the others, though this difference is not so marked as is the 

 case with Coelenterata. 



It will also be observed that the yearly maxima of records for the 

 various stations are not so regular, and also that the larger of the monthly 

 records occur during the summer months. 



* Fifteenth Annual Report of Fishery Board for Scotland. Part hi. Pp. 175-193. 



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