204 



tal lamella, the distal edge of which is minutely crenulated throughout. Seg- 

 ments of mesosome sharply defined, with the posterior edge forming on each 

 side of the median line a slight elevation, lateral parts distinctly bipartite, an- 

 terior lobe thickened, truncate; coxal plates well defined, though rather small, 

 with the edges irregularly lobular or coarsely crenulated. Metasome rather nar- 

 row, and scarcely occupying more than 1 / i of the length of the body, epimeral 

 plates discontiguous, narrow lanceolate arid resembling the lamellae of the pleo- 

 poda. Eyes very small, though distinctly observable. Antennse of normal struc- 

 ture. Terminal joint of maxillipeds very small, nodiform, and imperfectly de- 

 fined. 1st pair of incubatory plates with the terminal lobe well defined; the 

 succeeding pairs very large, arching over the ventral face. Legs of the usual 

 structure, slightly prominent laterally. Pleopoda with the lamellse lanceolate 

 and obscurely tubercular. Uropoda somewhat asymmetrical, resembling in size 

 and structure -the epimeral plates. Male rather broad, depressed, with the ce- 

 phalon obtusely truncated in front, and all the segments very sharply marked 

 off, from each other, those of metasome narrowed abruptly to a width much 

 narrower than those of mesosome ; last segment bilobed. Colour not yet stated. 

 Length of female reaching to nearly 15 mm., that of male 4 mm. 



Remarks. — This is a very distinct species, though unquestionably refer- 

 able to the genus Pseudione. Its specific name refers to the peculiar crenu- 

 lation of both the frontal edge and the coxal plates in the female. It is by far 

 the largest of the Norwegian Epicarida. 



Occurrence. — Two specimens of this form were secured during the 

 Norwegian North Atlantic Expedition, both having been extracted from the bran- 

 chial cavity of young specimens of Munida rugosa, taken of the Romsdal coast. 

 They were provisionally determined as Pleurocrypta galathew Hesse, and were 

 recorded under that name in my account of the Crustacea of that Expedition. 

 Another ^specimen, the one from which the accompanying figures have been 

 drawn,' and exactly agreeing with the 2 other specimens, was recently forwarded 

 to me from the Museum of Copenhagen, still resting on its host, a nearly full 

 grown specimen of Munida tenuimana, G. 0. Sars. The latter was taken by 

 Dr. Petersen in the Skagerak near the Norwegian coast, from a depth of 275 

 fathoms. The parasite had caused a very conspicuous deformity off the carapace 

 of the Munida, . the right branchial region being greatly distended, so that it 

 was necessary to break off a piece, in order to extract the parasite in an un- 

 damaged state. Its marsupial pouch contained an immense quantity of embryos 

 in ' the lastj stage of development, and exhibiting the appearance common, it 

 would seem, to all the BopyridEe. It may be noted, that only in two other in- 



