— 10 — 



majority of the specimens seen by me are immature and 

 the material in the Copenhagen Museum does not even 

 contain any adult male, but several adult males are found 

 in the collection of the U. S. Nat. Museum. The eyes of 

 the adults are sometimes slightly ovate and without con- 

 striction, but generally conspicuously higher than broad 

 and frequently with a discernible constriction ; in 

 younger specimens the eyes are somewhat or considerably 

 higher than broad, with the constriction frequently well 

 developed. As in R. in er mi s the carapace has no lateral 

 denticles, sixth abdominal segment has a terminal upper 

 spine ; sixth and seventh pairs of thoracic legs as in that 

 form. The first pair of legs, developed as prehensile 

 organs, must be dealt with more explicitly. 



In a large number of from less than half-grown to not 

 quite full-grown specimens taken off South-Iceland the 

 prehensile legs are long and very strong, with the fourth 

 joint reaching a little or somewhat beyond the end of the 

 antennular peduncles ; these legs have second and thirds 

 joint and the proximal part of the elongate fourth joint 

 exceedingly thick as compared with these joints in second 

 pair; the distal part of fourth joint and the major proxi- 

 mal part of the elongate fifth joint are nearly naked, 

 while the distal part of fifth joint has a few short, nearly 

 spiniform setae on the lower margin ; the seventh joint is 

 as broad as the strong sixth, much shorter and thicker 

 than in second pair, and the setae on sixth and seventh 

 joint are naked, stiff, nearly spiniform. These prehensile 

 legs are thus extremely different from the corresponding 

 pair in R. in er mis. 



In adult females taken off Cape Cod the prehensile legs 

 are about as in the specimens just decribed, with their 

 fourth joint reaching somewhat beyond, or only to the 

 end of, the antennular peduncles. In several subadult 

 specimens taken, together with a number of R. inermis, at 

 a station off South-West Iceland, the prehensile legs vary 

 much in length with corresponding thickness ; in one 



