92 



Occurrence. It would seem to be a very rare species. The first specimen 

 was found by the present author on the Storeggen bank, clinging to a spine of 

 Echinus rarispinus G. 0. Sars, taken up from a depth of 80 to 100 fathoms. 

 Another specimen was taken off the Lofoten Islands in about the same depth. 



Distribution. Skagerak (Meinert). 



den. 2. ArCtUrella, G. O. Sars, n. 



Generic Characters. Body less elongated than in Astacilla, and in female, 

 slightly depressed, the middle segment being very large and broad, scutiform. 

 Metasome about as in Astacilla. Superior antennae with only a very restricted 

 number of olfactory filaments issuing from the tip of the flagellum. Inferior an- 

 tennae of no considerable length, flagellum 3-articulate and terminating in a 

 long spine. Maxillipeds with the palp rather slender, 5-articulate, epignath very 

 large and ciliated at the tip. 1st pair of legs with the proximal part of the 

 dactylus narrow^, linear; the 3 succeeding pairs less elongated than in Astacilla, 

 and less richly supplied with seta:. Incubatory pouch confined to the middle seg- 

 ment of mesosome. Male much smaller than female, and having the middle seg- 

 ment of mesosome simple, cylindric in form. 



Remarks. This new genus is founded upon the peculiar form described 

 by the present author as Astacilla dilatata. A closer examination of this form 

 has shown it also to differ from the species of the genus Astacill't in some ana- 

 tomical details mentioned in the above diagnosis, so that it should more properly 

 be regarded as the type of a distinct, though nearly-allied genus. 



Arcturella dilatata, G. 0. Sars. 



(PL XXXVIII.) 



Astacilla dilatata, G. 0. Sars, Oversigt af Norges Crustaceer I, p. 63, PI. 2, fig. 3. 



Specific Characters. Body of female very tubercular, some of the tu- 

 bercles assuming a spiniforin character. Cephalon with 2 dorsal juxtaposed, and 

 somew r hat procurved pyramidal prominences, in front of which occur several smaller 

 tubercles. Each of the 3 succeeding segments with a transverse series of 5 co- 

 nical tubercles, the median one being the most prominent, lateral parts triangu- 

 larly produced, those of 1st segment larger and deeper than those of the 2 other 

 segments. Middle segment of mesosome exceedingly large and broad, somewhat 



