142 



Occurrence. I first discovered this form off the Lofoten Islands, in depths 

 ranging from 120 to 250 fathoms, and have subsequently found it in 2 other 

 localities of the Finmark coast, viz., Hasvig and Vadso. South of the Lofoten 

 Island, I have not yet met with it, and it would therefore seem to he a northern 

 form. Its swimming motions are exceedingly rapid, and, as in the allied forms, 

 are effected by abrupt bounds backwards. Out of Norway, it has not yet been 

 recorded. 



Gen. 5. Pseildarachna, G. 0. Sars, n. 



Syn: llyaraclma, G. O. Sars (part). 



Generic Characters. Body clavate in form, with the anterior division con- 

 siderably broader, and scarcely shorter than the posterior, being defined from it 

 by a deep constriction. Cephalon large and broad, obtusely truncated in front. 

 The 4 anterior segments of mesosome scarcely excavated transversally, 2nd seg- 

 ment much the largest; the 3 posterior segments but slightly expanded. Caudal 

 segment comparatively large, oblong triangular. Superior antennae very small, 

 and placed far apart, basal joint lamellarly expanded on the outer side, nagellum 

 poorly developed. Inferior antennae strongly built, with the flagellum longer than 

 the peduncle. Mandibles very large, with blunt, undivided cutting edge, molar 

 expansion extremely minute, dentiform, palp absent. Maxilhe and maxillipeds 

 about as in the preceding genera. 1st pair of legs very slender, nearly filiform; 

 2nd pair, on the other hand, rather strongly built, and considerably longer than 

 the 2 succeeding pairs. Natatory legs rather poorly developed, 1st pair the 

 largest, last pair extremely slender. Uropoda lamellar, with a single very small, 

 nodiforui ramus. 



Remarks. The present new genus is established to include the very 

 anomalous form previously described by the present author as Ilyarachna hirsiita. 

 The differences which this form exhibits from the other Munnopsidce, are so 

 numerous, and of such an essential nature, that it can hardly be included in any 

 of the above-described genera, but must take its place in a separate genus. The 

 structure of the legs in particular is rather peculiar, and that of the mandibles 

 is also pronouncedly different from that found in the preceding genera. 



