AT 
viz. Spher. Munnopsidis and the two species of Choniostoma, lay the largest number of 
eggs. In a specimen of Ch. mirabile with eleven ovisacs 1 counted the eggs in one of these 
presumably of middle size, and I found 1057 eggs, so the number of eggs laid by this 
specimen may be said to amount to 11,620, and if we take this figure as the normal 
quantity in Ch. mirabile of the Kara Sea, at any rate we do not exaggerate. In Spher- 
Munnopsidis the number of eggs seems to be even much higher, however, it would scarcely 
be possible to calculate the exact amount. Between these last-mentioned species and 
Stenothocheres egregius the other species present a variety of transitions, as far as fertility 
is concerned. In a following chapter about distribution etc. I shall have an opportunity 
of making some further observations on these rather remarkable differences. 
Il. The development of the eggs. As for the division of the germ and the earlier 
part of the embryological development, which I have not studied myself, I shall refer to the 
representation of Salensky. As in all Copepoda a Nauplius stage is developed (pl. XI, fig. 1¢ 
and fig. 1d); but this stage never becomes free, it evolves itself into the stage of a highly 
organised larva, of which a detailed description is given below. When this larva, which 
corresponds with the first Cyclops stage in other parasitic Copepoda, is full-grown, it breaks 
out of the egg-membrane and of the ovisac. As for the details concerning the development 
of the Nauplius stage and of the larva, I must again refer to Salensky. 
It may be added that in material preserved in spirit (and I have seen no other) 
the ovisacs, when younger, are of a light yellowish colour, but they gradually get whiter, 
as the larve are developed. 
d. The free Larva. 
I. The Material. Of several species 1 have found free larve, which were either 
swimning out of, or had recently swum into the marsupium, and these specimens, of course, 
were excellent, showing the normal shape of the larve. Of a number of species I have 
procured a rich material of larva by pulling them out of an ovisac; they were good enough 
when taken while about to break out of the egg-membrane, though the body might be 
somewhat soft and not extended in its full length,» thus showing a vaguer outline which did 
not quite correspond with that of the swimming specimens. Sometimes I had to content 
myself with younger animals, which had to be pulled out of their egg-membranes, and which 
had indeed a well-developed mouth, maxilla, maxillipeds etc., but whose cephalothorax was 
decidedly shorter and stouter than those of the full-grown larve, and which also showed 
other signs of unfinished development, so that no reliable observations could be made of 
difficult parts, as e.g. the branches of the maxillule. Finally, of a few species I had only 
larvee which had swum into the marsupium of a new host, where they had attached them- 
selves (9: below), and in these the cephalothorax, as a rule, was shorter and broader 
than in the free specimens. Of some species I had larve of this kind as well as of others, 
