134 



with the carpal joint oblong fusiform in outline, propodal joint oval, somewhat 

 shorter, hut scarcely narrower. Uroporla about half as long as the caudal seg- 

 ment, dislal joint scarcely longer than the proximal one, both being clothed with 

 scattered bristles. Colour pale reddish brown. Length of adult male 11 mm. 



Remarks. — As above stated, this remarkable form was detected by my 

 late father in the year 1860, and was briefly characterised in the above-mentioned 

 journal. Subsequently a fuller description, accompanied by figures, was given 

 in his paper on the fauna of the Cbristiania Fjord inserted in „Nyt Magazin for 

 Naturvidenskaberne". It is much the largest of the Norwegian Munndpsidce. 



Occurrence. — The species occurs along the whole Norwegian coast, from 

 the Christiania Fjord to Vadso, in depths ranging from 60 to 400 fathoms. In 

 some places I have found it in great abundance, especially in the deeper parts 

 of the Christiania and Trondhjem Fjords, as also off the Lofoten Islands. I have 

 several times observed it in a living state, and watched its curious movements. 

 It swims backwards in long, though not particularly rapid bounds, and during 

 this movement the long inferior antennae and the 3rd and 4th pairs of legs are 

 extended straight in front. Immediately on reaching the bottom, the antennas 

 and legs are spread out laterally, and the animal now moves slowly about in the 

 ordinary creeping manner. The appendages are extremely fragile and liable to 

 be broken off from the body, for which reason it is rather difficult to get specimens 

 in quite an uninjured state. 



Distribution. -^Skagerak (Meinert), Greenland (Hansen), Spitsbergen (Buch- 

 holtz), the Barents Sea (Hoek), Franz Josef Land (Heller), the Kara Sea (Hansen), 

 Arctic America (Miers), Atlantic coast of North America (Harger). 



Gen. 2. Ilyaraehna, G. o. Sars, 1863. 



Syn : Mesostenus, G. 0. Sars (olim). 



Generic Characters.— Body rather compact, clavate in form, attenuated 

 behind, with a very strongly marked median constriction. Cephalon very large 

 and broad, transversely truncated in front, dorsal face evenly vaulted, lateral 

 jmrts greatly expanded. The 4 anterior segments of mesosome closely crowded 

 together, and slightly excavated transversally ; the 3 posterior segments large and 

 convex above, 5th segment scarcely narrower than the preceding segments, and 

 deeply emarginated behind. Caudal segment narrow, triangular in form. Superior 



