105 
females sectioned in various directions, the conclusion has 
been arrived at that the spermatozoa at once pass up the 
rudimentary oviduct to the ovary and fertilise the eggs. 
This probably accounts for the difference between the 
ovary of an adult Lernwa and Lepeophtherrus. No trace 
of a receptaculum seminis could be made out in the adult. 
Lire History. 
The development of the embryo has not been worked 
out by the present author. An excellent work by D. 
Pedaschenko* contains a full description and figures of 
the developing embryo. 
The young Lernea hatches out as a nauphus, with 
three pairs of appendages, representing the rudimentary 
antennules, antenne, and mandibles (Plate IV., fig. 2, 
nat. size, “45 mm.). It then after a short pelagic life, 
settles on the apex of the gill filaments of the flounder, 
to which it adheres by a broad chitinous filament, and 
passes into a cyclopoid form (Plate IV., fig. 4). The 
young Lernea are occasionally found on the gills of the 
plaice and lumpsucker. The parasite, by its attachment 
to the gill filament, produces a marked change in that 
organ. The whole of the apex assumes a tumid character, 
and the filamentous plates on both sides for some little 
distance disappear (Plate IV., figs. 8 and 9). While 
attached to the gills the various appendages develop. The 
male here reaches maturity (Plate IV., fig. 5), and under- 
goes no further change. In the female a considerable 
lengthening of the genital segment accompanies the 
appearance of the various appendages. Fertilisation next 
takes place; then the young female severs its connection 
* Development of the embryo and metamorphoses of Lernwa branchia- 
lis. Trad. Soc. Imp. des Naturalistes de St. Petersbourg, vol. xxvi., 
livr. 4, No. 7, Sect. de Zool. et de Physiologie, 1898, in Russian, with 
German resume. 
