76 



curtvpes came from a depth of a hundred fathoms. Possibly a large part of the specimens 

 of the three forms which live on Mysidacea were taken as far down as one to two hundred, 

 some even to three hundred fathoms, but as the hosts in question may occur in a depth of 

 less than a hundred fathoms, I cannot say anything definite about them. So it may be 

 stated here, that in the material from the »Ingolf« expedition I found a couple of specimens 

 parasitic in Cumacea, from a depth of respectively a thousand and thirteen hundred fathoms, 

 which sufficiently proves that the family also occurs in a very considerable depth. 



j. Geographical Distribution of the particular Species relatively to 



that of their Hosts. 



It appears from the preceding paragraph that each of the forty of my species was 

 taken in one particular country (as Denmark, Norway, Sicily etc.), or in a particular, com- 

 paratively smaller sea. Only three species (Sphceronella microcephala, S. decorata and 

 Ghoniostoma Hansenii) show a wider distribution. As a matter of course, we shall gradually 

 find that most species of Choniostomatidse have a much wider range than is known at present, 

 but from this I do not think we can draw the conclusion that they are as widely dispersed 

 as the species on which they live. In a smaller material of Iphinoe trispinosa (Goods.) 

 from Messina I found seven specimens with parasites, one specimen even with two parasitic 

 species, but in a larger material of the same species from Denmark I have been unable to 

 find a single parasite. In a pretty considerable material of Calliopius Iceviusculus (Kr.) from 

 the East-coast of Asia between lat. 40° and 51 ° N. I found seven specimens with parasites 

 {Sphceronella Calliopii), but my examination of several specimens from West-Greenland, and 

 numerous specimens from Denmark, gave a negative result. (Yet it must be mentioned that 

 Sars, in his work on the Amphipoda, considers the Danish specimens to belong to another 

 species, Call. RatMei (Zadd.), but I doubt whether this will be maintained in the future). 

 Several specimens of Hippolyte Gaimardii M.-Edw. from the Kara Sea were infested; at 

 the most northern coast of Norway, Sp. Schneider, and at West-Greenland E.Vanhbffen, have 

 found Ghoniostoma in the same species, but I have examined without result a very large 

 material of the same Hippolyte collected from numerous localities near the Danish coast, 

 and I feel inclined to think that these parasites do not occur in the waters surrounding 

 this country. The same may be said about Biastylis RatMei (Kr.), of which in about half 

 of the females with marsupium from West-Greenland and from the Kara Sea, I found 

 Sphceronella decorata, whereas of the same species from different Danish localities I have 

 examined at least several scores of adult females without finding any parasite. 



k. Frequency of the Parasites in proportion to their Fertility. 



In mentioning the eggs of the parasites, I pointed out (p. 46 — 47) the enormous difference 

 of fertility between the species with very small and those with very big females. Of 



