98 Dr. R. Kossman on the Entoniscidee. 
something of importance on the developmental history. But 
what Fritz Miiller (1, p. 12) says of Hntoniscus, namely 
that it ‘‘ accumulates a whole series of consecutive broods 
about it simultaneously, so that the material for the whole 
developmental history might be obtained from the brood-leaves 
of the same animal,” is incorrect, either everywhere or, at 
any rate, for the Kuropean Entoniscide. Rearing experiments 
of all kinds that I have instituted have, however, always mis- 
carried, so that I have never obtained any stages which had 
not already been observed by my predecessors. I must there- 
fore confine myself to one or two corrections with regard to 
the newly hatched larva. The pleopoda of the larva do not 
resemble those given by Fraisse and Giard, but, even in the 
case of our species, exactly those given by Fritz Miller 
(1, pl. i. figs. 11, 12) for H. porcellane. The outer an- 
tenna figured by Fraisse is imperfect. See my figure 6 
(Pl. LX.). 
In opposition to the differences between the embryos of #. 
porcellane and H. eancrorum, which Fritz Miller found and 
arranged in a table, which was afterwards completed by Giard 
(5, p. 697) for H. Cavolinii, I have also something to say. 
I believe that these are not specific differences, but differences 
of age, both of which, however, are passed through within the 
host. Even @ priort such important differences in embryos 
of such similar animals are very remarkable and doubtful, 
and it is interesting to see what strenuous efforts Fraisse has 
made (4, p. 28 et segq.) to bring these statements into accor- 
dance with the Darwinian theory. 
As a matter of fact, however, Giard finds the larve of #. 
Cavolintt very similar to those of H. canerorum, and different 
from those of 4. porcellane, especially as regards the deve- 
lopment of the last pair of pereiopoda; whilst, on the con- 
trary, Fraisse and I find the larve of . Cavolini rather to 
agree with Fritz Miiller’s description of the larvee of £. por- 
cellane ; and Fraisse asks directly ‘‘ why the larva of EZ. Cavo- 
linit has not also undergone a similar metamorphosis of the 
sixth pair of legs’’—to which, indeed, he finds only a very 
hypothetical answer. 
Both larval forms, therefore, appear to exist in L. Cavolinit. 
If we remember further that the seventh segment of the pereion 
ig wanting in the larva of £. porcellane, but present in that 
of LH. cancrorum, that the pencil of olfactory threads cha- 
racteristic of older Bopyrid larve is wanting in the former 
(see 1, pl. ii. fig. 4) and present in the latter (2, pl. in. 
fig. 3), that the pleopoda in the former are less and in the 
latter more richly setigerous, and, finally, that the former is 
