454 SOME RESULTS OF THE INTERNATIONAL FISHERY INVESTIGATIONS. 



which ill thirty minutos captured aliout seven thousand speciuiens of 

 young stages of pelagic and bottom-living fishes, belonging to twenty- 

 two dillerent species. We are assured that this haul is " far from being 

 the richest in individuals made by the Thor." No method of investigation 

 practised in the past afTorded this wealth of material. Not only are 

 naturalists nowadays in possession of a means of research enabling them 

 to obtain rich stores of material for the study of the developmental 

 histories of fishes, but they are also able to form reliable estimates of 

 the wealth of fish life in the sea at early stages, and to trace with some 

 probability the migrations of the larva; and young fishes. The first 

 results of the study of developmental histories of fishes made by the 

 help of those fishing apparatus are published in the Danish Meddddser. 

 In the paper already referred to Joh. Schmidt gives the first instalment 

 of a study of the free-swimming post-larval stciges of the fishes of the 

 North Atlantic belonging to the genus Gadus. This monograph 

 includes the cod, coal-fish, whiting, haddock, pollock, and other less 

 known gadoid fishes, and in it the author attempts, for the first time, a 

 systematic description of the characters of the post-larval fishes at 

 dillerent stages. It is well known that the recognition of young fishes 

 in their very early life is a task of much difficulty, and some con- 

 siderable degree of uncertainty has always attended the identification of 

 nearly allied fishes, such as the cod, haddock, and whiting, in the stages 

 following the metamorphosis, and before the little fish assumes the well- 

 known characters of the adult. V>y making a systematic study of the 

 colour markings of the young fishes, which, it should be remembered, 

 are quite different from those of the adult, Schmidt has been able to 

 classify the post-larval fishes of the cod family in much the same way as 

 the adults have been treated. The identification of these young fishes 

 has therefore been greatly facilitated for future observers. Making use 

 of material collected also by the young-fish trawl of the Thor, Schmidt* 

 has also given us by far the most complete accounts of the life histories 

 of the halibut and torsk (or tusk) in the literature. The description of 

 the series of stages of the halibut is particularly welcome, since the 

 development of this fish is more obscure than that of any other of the 

 fiat-fishes. Again, the early stages of the long rough dab, a fish 

 relatively common off the east coast of Britain, have been studied by 

 Petersen, and our knowledge materially advanced, f 



But by far the most important contribution to our knowledge of the 

 early life histories of edible fishes is the discovery by Schmidt and 

 Petersen! of the spawning place of the European fresh-water eel. The 



Meddelelscr Kovnn. llavundcrsog., Bd. i. Fiskeii, Nrs. 3 and 8, 1904-5. 

 t Meddelelscr Komm. Ilavundersocj., Fiskeri, Bd. i. Kr. 1, 1904. 

 X Ibid., Fiskeri, Bd. i. Nrs. 5, 6, 1905. 



