232 



shorW than the inner. Male not passing beyond the last larval stage, and indistin- 

 guishable from the female larva, except by the presence of the male generative 

 organs, which form 2 small bags within the last segment of mesosome. Ovaries 

 of female sometimes fully developed even in the last larval stage. Parasitic on 

 Crustacea of very different orders, more generally occurring within the marsupial 

 cavity of their hosts. 



Remarks. — Under this head I combine the four families, Cyproniscidce, 

 Cabiropsidce, Podasconidce and Cryptoniscidw of MM. Giard and Bonnier. The 

 chief motive which has led the above mentioned authors to the establishment of 

 these four families, seems to have been the occurrence of the parasites, each 

 family containing only forms which are stated to infest one group of Crusta- 

 cea. In my opinion, however, this circumstance cannot be regarded as a suffi- 

 cient criterion for the distinction of separate families, unless there are also found 

 very essential differences in the structural relations. This, indeed, seems, not to 

 be the case, and the last larval stage in particular, as also the male, in all these 

 forms is of a very uniform appearance, and easily distinguishable from that of the 

 2 above-described Bopyroid families. 



The earliest known genus, from which the family has derived its name, 

 is Cryptoniscus, established by Fritz Muller for a peculiar parasite found on a 

 Peltogaster infesting a Brasilian Pagurid, and having in its adult state a perplex- 

 ing resemblance to a Planaria, hence the specific name planarioides. Subse- 

 quently several other genera have been established, amounting to about 12 in 

 all. Of these, 5 will be described below, of which 4 at least are stated to 

 be represented in the fauna of Norway. 



Gen. 1. CyprOniSCUS, Kossman. 1884. 



Generic Characters. Body of adult female forming an inert curved sac 

 wholly filled with ova or embryos, and affixed to' the host by the aid of a thin 

 flexible chord ; dorsal face convex and exhibiting distinct traces of segmentation, 

 ventral face flattened, lateral parts expanded, anterior extremity broadly produced, 

 posterior obtusely rounded and incurved. — Body of immature female sub-pyri- 

 form, bluntly truncated in front, hind extremity narrowly exserted, lateral parts 

 not distinctly defined. — Body of young _female, „imed2ately^_after_ the_ trans- 

 formation, subfusiform, very faintly segmented, front part still enveloped by the 



