227 



ally as regards the oral parts and the incubatory plates. The larva figured at the 

 bottom of the accompanying plate was taken from the marsupial room of a speci- 

 men, in which the greater part of the brood had been discharged, so that only a 

 few larva still remained. On comparing this larva with that from Nansen's Expedi- 

 tion figured on PL 94 and adduced to Dajus mysidis, an unmistakable resem- 

 blance between the two will be found to exist, especially as regards the peculiar 

 structure of the uropoda. 



Occurrence. — I have found this form only on a single species of deep- 

 water Mysidse, viz. Amblyops abbreo'vlta, G. 0. Sars. All the specimens were 

 found attached to the same place on their hosts, viz., to the dorsal face of the 

 3rd segment of the metasome, and in all the cases the parasite was found to 

 turn its head forwards in relation to its host, as shown, by fig. X. This is 

 a rather anomalous position, and MM. Giard and Bonnier are therefore inclined 

 to believe that my statement about this point might be due to some mistake, and 

 that the parasite might in reality have had its head turned to the opposite side. 

 Though none of my specimens are now in their original connection with their hosts, 

 I must still insist on the correctness of my statement. Nor is such a position 

 quite exceptional among the Epicarida, for, as stated above, the Micronisci 

 as a rule occupy a similar position in relation to their hosts, and farther below 

 a Cryptoniscid will be described, Cyproniscus cypridince, which also, in its fully 

 grown state, invariably turns its head to the same side as that of its host. 



As to the distribution of the present form, I have found it in two rather 

 distant localities of the Norwegian coast, viz., at Mosterhavn in the outer part 

 of the Hardanger Fjord, and at Bejan outside the Troudhjemsfjord. Out of 

 Norway this form has not yet been recorded. 



Gen. 3. AspidOphryXUS, G- 0. Sars, 1882, 



Generic Characters. — Body of female shield-like, convex above, concave 

 below, without any distinct boundary between its chief divisions, and with only 

 very slight traces of segmentation. Cephalic part projecting in front between 

 the largely developed, wing-like lateral parts of the mesosome, its ventral face 

 forming a horizontal quadrangular plate defining the very small rounded oral 



