The larval development of Meganyctiphanes norvegica in the Clyde sea area has been investigated and found to be different from that described by Macdonald (1927 b). The conclusion is reached that it can be divided into four phases, these being termed furcilia I, II, III and IV. A few notes on larval ecology are presented.
The facts required to elucidate the course of development in any one euphausiid species are discussed. It is pointed out that the environmental conditions appear to affect the development.