148 
little shorter than the first one, and somewhat longer than the third one combined with the 
not defined caudal stylets; the terminal sete 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. 2k) 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 larve), 
and finally, two larvee 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 larvze); 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. Guard and Bonnier have described the female and 
ovisacs of a species taken in Ampelisca tenwicornis 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 they have occurred only in fully developed marsupia. 
These five species show mutually very great ditference in both sexes, nevertheless, they are 
distinguished in several features from the species found on Amphipoda; the larve of all 
these parasites, especially, are characterised by some peculiarities which are not noticed in 
any of the previously described larve, 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 larvee of each species, it may be to the purpose to give a 
view of their peculiarities. 
THE FEMALES. Antenne 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 
