148 



little shorter than the first one, and somewhat longer than the third one combined with the 

 not defined caudal stylets ; the terminal setae of these stylets almost two thirds the length of 

 the whole body. 



POST-LARVAL DEVELOPMENT. After the preparation I found on the object- 

 glass an individual (fig. 2 k) which I consider to be a pupa of this species; it is mentioned 

 above on p. 61. 



HABITAT. The marsupium of Ampelisca typica Sp. Bate from Denmark. In one 

 specimen occurred: one female, two males, twelve ovisacs, three of which were free, and 

 nine adhering to each other in a lump (two of them with scarcely quite developed larvae), 

 and finally, two larvae which had evidently been attached. In another specimen were found : 

 one female and some ovisacs; in a third: one female and fifteen ovisacs, thirteen of which 

 adhered to each other in a lump (and one of them contained developed larvae); in a fourth 

 specimen were found: one male (the largest represented), two free ovisacs and two of the 

 host's own eggs. 



REMARKS. This parasite in all its stages is far removed from all other species 

 of this genus, still the differences are not of such a quality that I have felt justified in 

 establishing the species as a type of a new genus, as which, in my eyes, it would not be 

 fully equivalent to the other genera. Giard and Bonnier have described the female and 

 ovisacs of a species taken in Ampelisca tenuicomis Lilljeborg from le Croisic (Brittany), 

 but in spite of the great differences between their description and my own of the head and 

 its appendages, I nevertheless consider my species identical with theirs, and I refer to my 

 detailed critique of their account given above on page 13 — 14. 



b. Parasites on Cumacea. 



In six species of Cumacea I have found parasites in the marsupium, and I have 

 referred them to five species. Hitherto the} 7 have occurred only in fully developed marsupia. 

 These five species show mutually very great difference in both sexes, nevertheless, they are 

 distinguished in several features from the species found on Amphipoda; the larvae of all 

 these parasites, especially, are characterised by some peculiarities which are not noticed in 

 any of the previously described larvae, whereas a few of them appear in the larva of 

 S. Munnopsidis which lives in Munnopsis typica M. Sars belonging to the order Isopoda. 

 For several reasons, among others in order to avoid unnecessary repetitions in the descrip- 

 tion of the two sexes and the larvae of each species, it may be to the purpose to give a 

 view of their peculiarities. 



THE FEMALES. Antennae only 2-jointed or, mostly, wanting. The mouth-border 

 moderately broad or narrow. The basal joint of the maxillipeds decorated on the anterior side 

 with small groups or rows of very short or rudimentary hairs, which, in many cases, only look 

 like small, distinct dots ; the spine proceeding from the distal inner angle of the penultimate 



