242 TREUBIA VOL. II, 2—4. 
attachment is effected by means of long adhesive threads forming part of 
the egg-membranes. The eggs are globular, but the diameter is not always 
exactly equal in all directions. Below will be found the maximum and 
minimum diameters of a number of live eggs, artificially fertilized twice 
twenty-four hours before they were measured: 
1.43 — 1.52 m.m. 
1.45 — 1.50 m.m. 
1.45 — 1.55 m.m. 
1.48 — 1.57 m.m. 
1.50 — 1.50 m.m. 
1.50 — 1.52 m.m. 
1.50 — 1.53 m.m. 
1.50 — 1.55 m.m. 
1.50 — 1.55 m.m. 
1.50 — 1.55 m.m. 
1.50 — 1.60 m.m. 
1.50 — 1.60 m.m. 
1.52 — 1.60 m.m. 
1.55 — 1.58 m.m. 
1.55 — 1.60 m.m. 
We may therefore say that the average diameter of the kepala timah 
egg is about 1'/, m.m.. The smallest diameter measured was 1.43, the 
largest 1.60 m. m.. 
It should be remembered that these are dimensions of eggs spawned 
in brackish or even in salt or very salt water by fishes which had also 
grown up in similar water. It is not beyond the bounds of possibility 
that the eggs of kepala timah that have always lived in fresh water and 
also spawned in fresh water, may be larger. For indeed there are exam- 
ples of fish-species, such as the plaice (Pleuronectes platessa L.) in the 
Baltic, whose eggs are larger according as the salinity of the milieu is lower. 
The kepala timah egg, as may be seen in figures 17—21, always 
possesses a large number of oil-globules which never unite’ into one 
larger globule. When not too weakly magnified the egg-capsule displays 
a number of fine dots. Furthermore it is surrounded on the outside by the 
long adhesive-threads already mentioned. With the eggs still lying in the 
ovarium these adhesive threads are curled up closely against the egg-capsule, 
as is reproduced in figure 17. In a certain place the threads display a 
radiate arrangement as is noticeable not only in figure 17 but also in the 
figures 18, 19 and 20. 
Now the egg of the Teleostei is often provided with two envelopes, 
viz. an internal egg-membrane or zona radiata (=egg-capsule, W. HIS (®)) 
and an external egg-membrane or zona villosa (= “Zottenschicht”; 
cf. O. HERTWIG, Handbuch (?°)). The two membranes together are 
