240 



anal segment rounded at the tip. Eyes wanting. Basal expansion of antennulse 

 very broad, and divided into 21 closely crowded teeth. Antennae with the fla- 

 gellum scarcely longer than the last 2 joints of the peduncle combined. Uropoda 

 with the outer ramus about half as long as the inner. Length of adult female 

 about 4*/2 mm., of male 0.65 mm. Parasitic on Idothea baltiea. 



Remarks. -As above indicated, the differences between this form and the 

 other species recorded by MM. Giard and Bonnier, C. Meinerti, are very slight, 

 and it is, indeed, chieflv the occurrence of both forms that has led the said 



f V 



authors to regard them as 2 distinct species. It may be that a closer compara- 

 tive examination of young females specimens, males and larvae, might reveal better 

 distinguishing characters ; but the adult females, at least, of these 2 forms appear 

 to me to be nearly undistinguishable from one another. 



Occurrence. This form has certainly not yet been recorded from Nor- 

 way; but, as the species of Isopod, Idothea baltiea Pallas, on which it is found 

 parasitic, is very common along our whole coast, it is very probable that, on a 

 closer investigation, it will in reality be found to exist also off the Norwegian 

 coast. The figures here given are from Danish specimens kindly sent to me from 

 the Museum of Copenhagen. In none of these were fully developed embryos 

 found, and I have therefore not been able to give any figure of the characteristic 

 1st larval stage. The specimens examined by MM. Giard and Bonnier were 

 likewise from the Danish coast, and this form has. indeed not yet been found 

 in other places, unless the Greenland form, C. Meinerti, should prove to be the 

 same species. 



Gen. 5. MunnOniSCUS, Giard & Bonnier, 1895. 



Generic Characters. Body of adult female forming a thin-skinned sac 

 of a somewhat irregular bilobed form, without any traces of segmentation, but 

 exhibiting dorsally a well defined, though rather small opaque area; that of 

 younger female more regular in form, with the opaque area occupying almost the 

 whole dorsal face. No distinct affixing apparatus present. Male unknown. Para- 

 sitic in the incubatory pouch of Isopoda belonging to the family Munnopsidce. 



Remarks. This genus was proposed in the year 1895 by MM. Giard and 

 Bonnier, to include the form previously recorded by the present author as 

 Cryptothiria marsupialis and, indeed, with some doubt referred by him to Dana's 

 genus. We only know at present of a single species, to be described below. 



