74 
which live in marsupia. In the afore-mentioned place it is stated that only in six cases I 
found the eggs of the host together with a parasite, and it may be added here that in 
almost 160 cases I only found parasites (one or more specimens), but no eggs of the host, 
in the marsupium. But at the same time I[ have stated that I have found no parasite on 
any specimen of Cumacea or [sopoda in which the marsupium was wanting, and of Amphipoda 
I have only found altogether twelve specimens belonging to four species, whose marsupium 
was either wanting or only half developed, and on which, nevertheless, I found parasites; 
all these, without exception, were half-mature or tiny females, or larvee (one male). However, 
this material is too small to allow me fully to adopt the opinion of the authors that the 
host »en g@énéral« is infested before its maturity; in the fully developed marsupium of 
several specimens of Corophiwm crassicorne Bruz. I have found only a half-developed or still 
younger female and either a male, a larva, or a pupa, but no adult females. But it is 
certainly an established fact that, as a rule, we notice a »castration parasitaire« in the 
hosts which have parasites in their marsupium. 
It is much more doubtful whether the four species living in the branchial cavity of 
Hippolyte and Cumacea, are usually, or sometimes, capable of causing a » castration parasitaire « 
of their hosts. In page 66, and particularly later on, in the systematic part, detailed infor- 
mation is given about the age and sex of these hosts, but I do not think we can draw 
definite conclusions from these statements. I have said that I have found specimens of 
Diastylis lucifera containing a female of Homocoscelis with the full number of ovisacs in 
the branchial cavity, and the young ones of the host in the marsupium, but knowing neither 
the time required for the development in the marsupium of the eggs and young ones of 
the host, nor the time required by the parasite for its own growth and the laying of all 
its ovisacs, it seems impossible to me to draw a definite conclusion with regard to a »ca- 
stration parasitaire«; however, that such a castration may take place, seems to follow from 
the aboye-stated fact that the marsupium of more than two thirds — namely thirty-one — 
of the infested adult females was empty, whereas in thirteen specimens it was filled with 
young ones; yet it must be observed that in the non-infested females, the marsupium was 
found to contain eges or young ones in 182 specimens, whereas it was empty in 74 specimens. — 
[t is rather probable that Aspidoecia Normani causes a castration, as the marsupia of the 
four infested females which were not occupied by Mysidion, were empty. 
The fowr species living in the branchial cavity of Hippolyte and Cumacea cause a 
swelling of the carapace of the host, which, to begin with, increases in size with the growth 
of the parasitic female, and thus — at least in Cumacea, and probably also in Hippolyte — 
continues gradually increasing with the number of ovisacs. In Hippolyte the swelling may 
reach the same size as if it enclosed a large Gyge, and in the subsequent description of 
Choniostoma Hansenii, it will be proved that this parasite itself produces the swelling. In 
Diastylis lucifera the swelling assumes a somewhat other shape, though it may be very 
conspicuous. 
