122 



one of the apical claws very slender and elongated. Natatory legs with the rami 

 more slender than in R. rufocincta and nearly equal in length, middle joint of 

 inner ramus considerably produced at the outer corner, terminal joint of same 

 ramus rather elongated, with the outermost of the setse of the inner edge trans- 

 formed to a slender, coarsely denticulated spine. Last pair of legs with the distal 

 joint much elongated, narrow oblong in form, inner expansion of proximal joint 

 comparatively short, triangular, not nearly extending to the middle of the distal 

 joint. Ovisac comparatively small, rounded. 



Male with the inner ramus of the 2nd pair of legs only very slightly 

 transformed. Last pair of legs with the distal joint considerably shorter than in 

 female and having the marginal setse spiniform; inner expansion of proximal joint 

 very slight, almost obsolete, with only 2 unequal marginal spines. 



Body of a dark yellowish hue, with the posterior half of the anterior 

 division tinged, especially along the ventral face, with deep chocolate brown. 



Length of adult female 0.74 mm. 



Remarks. This form, first described by Glaus, may be easily recognized 

 by its short, stout body, and especially by the unusual shortness of the uro- 

 some. Moreover the very sharp demarcation between the 2 chief divisions of the 

 body is rather characteristic. Though differing rather conspicuously in some of 

 the anatomical details from R. rufocincta, it ought in my opinion to be referred 

 to the same geniu, since in other respects these 2 forms exhibit a perfect agree- 

 ment. The Thalcstrls curticauda of Boeck is unquestionably identical with 

 Claus's species. 



Occurrence. I have taken this form occasionally off the south coast, more 

 frequently off the west coast, of Norway, in localities similar to those in which 

 R. rufocincta occurs. 



Dittrilntlion. Heligoland (Claus), British Isles (Brady), Spitsbergen (Scott). 

 Fran/, Josef Land (same author). 



. H2. Mierothalestris, G. o. Sars. n. 



('liitritcliT*. Body slender, subcylindrical in form, with no very 

 obvious demarcation between the 2 divisions. Cephalic segment of moderate size, 

 rostrum small, but well defined. Epimeral plates poorly developed. Urosome 

 with none of the segments expanded laterally; caudal rami short. Anterior an- 

 tcnnte attenuated, 9-articulate. Posterior antenna) with the proximal joint not 



