99 



HABITAT. The marsupium ofAmphipoda, Cumacea and Isopoda. Younger females 

 and animals in various stages of development of some species are also found on the ventral 

 surface of the thorax in Amphipoda. Found in Denmark, Norway, Greenland, in the Kara 

 Sea, the Mediterranean, off Cuba, and finally on the East-coast of Asia between about lat. 

 22° and 51 °N. 



REMARKS. This genus is very large. Subsequently thirty-four species will be 

 described, besides S. LeucJcartii Sal., which I have not seen (and S. diadema G. and B. 

 which has not been described). The above given diagnosis of the genus is rather meagre, 

 and it is easy to see that some of the characteristics are qualified by an » either . . . or«. 

 The obvious reason is that many of the species in several respects vary considerably among 

 themselves. Above, on p. 82 — 83 I have already given a general view of the most important 

 of these differences, stating my reasons for not feeling justified — in spite of these differences — 

 to divide the genus into several genera. 



It is impossible, for two reasons, to give complete analytical keys of the two sexes 

 in all species, firstly, because the male is unknown in nine species, secondly, because the 

 differences between the females and between the males in one small division are too vague 

 to be represented with sufficient preciseness in such a conspectus. However, in order to 

 procure a kind of general view, I will divide all species into three groups according to the 

 orders of their hosts , subsequently giving as good a conspectus as possible of each of the 

 two sexes in the species of each group. In this place I will only give the analytical keys 

 of the first division; the other keys will be found immediately preceding the divisions to 

 which they belong. 



a. Parasites on Amphipoda. 



It may be observed that the males of this group always have well developed trunk- 

 legs and caudal stylets. In the larvse the front is never furnished with processes or lists 

 in the sub-median part (there are one or two rather small lists near the basis of each 

 antennula), the basal joint of the maxilla is smooth, without combs, and the terminal joint 

 not serrated. 



1. Conspectus of the Females. 



The figures preceding the names of the species indicate their number in the subsequent 

 representation. In this conspectus all species are included except S. dbyssi n. sp., of which 

 my knowledge is too fragmentary (s. the description below). 



1. Head with distinct frontal border and distinct prominent lateral borders. Genital area 



broader than long 2 



13* 



