58 



BULLETIN 201, UNITED STATES NATIONAL MUSEUM 



two smaller spines. The cleft is armed with the usual teeth and shows 

 that peculiar dilation at the base to which Sars first called attention 

 in B. microps. This form of telson, relatively long and narrow, with 

 the sharply graded lateral spines, the strong terminal spine on each 

 apical lobe, and the cleft with the proximal dilation is characteristic 



Figure 12. — Boreomysis rosirata Illig ? : a, Antennal scale and peduncle, X 19; b, endopod of 

 second thoracic limb, X 19; c, telson, X 19; d, uropod, X 19. 



of B. microps G. O. Sars, B. rostrata Illig, B. inermis Hansen, and B. 

 verrucosa Tattersall, to the exclusion of all other described species. 

 B. microps is distinguished by the curious subchelate character of the 

 endopod of the second thoracic limb and B. verrucosa by the tubercles 

 on the carapace. The two remaining species, B. rostrata and B. 

 inermis, are extremely closely allied and in my judgment should be 

 united. They differ from each other mainly in the length of the 

 rostral spine. In B. rostrata it is comparatively long while in B. 



