74 



■\vliich live in mai-supia. In tlie 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 ofCumacea or Isopoda 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 larvae (one male). However, 

 this material is too small to allow me fully to adopt the opinion of the authors that the 

 host »en g6n6ral« is infested before its matiunty; in the ftilly developed marsupium of 

 several specimens of Corophium crassicorne Brnz. 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 brancliial cavity of 

 Hippolyte and Ciimsicea., 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 Homoeoscelis with the full number of ovisacs in 

 the brancliial 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 di-aw a definite conclusion with regard to a » ca- 

 stration parasitaii'e* ; however, that such a castration may take place, seems to follow from 

 the above-stated fact that the marsupium of more than two tliirds — namely thirty-one — 

 of the infested adult females was empty, whereas in tliirteen specimens it was filled with 

 young ones; yet it must be observed that in the non-infested females, the marsupium was 

 found to contain eggs or young ones in 182 specimens, whereas it was empty in 74 specimens. — 

 It 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 four species living in the branchial cavity of Hippohjte and Cumacea cause a 

 swelling of the carapace of the host, wliich, 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 Hanscnii, it will he proved that this parasite itself produces the swelling. In 

 Diastylis lucifera the swelling assumes a somewhat other shape, though it may be very 

 conspicuous. 



