lOG BULLETIN OF THE 



Cj Eye-peduncle t'usiibrni, cornea very small, not expanded. Rostrum 

 represented by a small pointed projection. 



4. B. microps G. O. Sars. Soutli of Nova Scotia, 1,250 fathoms. 

 (Chall. Scliizop. 18«5, p. 184, PL XXXllL figs. 7-10.) 



dj A lateral frontal spine over each eye, therefore the frontal margin 

 tliree-spined. Eye-peduncle conical, cornea expanded. 



6. B. tridens G. 0. Sars. Norway, 300-400 fatlioms. (Monogr. 



Norg. Mysid. 3, 1879, p. 10, Tl. XIV.) 



Cj Frontal margin obtusely rounded, without a rostral spine. Eye- 

 peduncles conical, cornea expanded. 



6. B obtusata G. O. Sars. Nortli Pacific, 345 and 2,740 fathoms. 

 (Chall. Schizop. 1885, p. 182, PI. XXIII. figs. 1-6.) 



bj Eye-peduncles constricted, very thin and cylindrical at the base. Cornea 

 greatly expanded, pnjjectiiig laterally considerably beyond the carapace. 

 Frontal margin obtusely pointed, without a rostrum. 



7. B. mefjdlops G. Sars. Norway, 80-200 fathoms. (Monogr. 



Norg. Mysid. 3, 1879, p. 18, PI. XV., XVI.) 



a^ Eyes imperfectly developed, calyciform, without pigment or visual elements. 



8. B. scijphops G. O. Sars. Arctic and Antarctic, deep-sea. 



(Nordhavs Exp. 1885, p. 56, PI. VL Chall. Schiz. 

 1885, p. 178, PI. XXXII. figs. 10-20.) 



Boreomysis californiQa, nov. spec. 



This new species agrees so closely in almost every regard with B. ardica, 

 that it is useless to give a detailed descripticm. The only diflerence I observe 

 is the peculiar character of the eye, whose cornea is somewhat less expanded, 

 and whose peduncle is prolonged over the cornea as a sharp conical tubercle. 

 The color of the cornea is pale brown, as in B. arctica (pigmento fulvescente). 



It is somewhat doubtful whether this species belongs to the genus Boreo- 

 mysis or to a new genus. The rudimentary condition of the pleopods and the 

 want of male appendages to the antennulpe show that the specimens are females, 

 but the incubatory lamellte are not developed. In the largest specimen I observe 

 at the base of the legs seven pairs of very little leaflets, which may be the seven 

 pairs of incubatory lamellae characteristic of the genus Boreomysis, and there- 

 fore I believe that this specimen, and also the two smaller ones, which do not 

 show these leaflets, are not fully developed females. On the other hand, in 

 case they are males, this species must be the representative of a new genus agree- 

 ing with tl?e genera Mysidella and Heteromysis in the rudimentary condition 

 of the male pleopods, but diff'ering in the structure of the other appendages 

 which are normally developed here. 



50 miles south of Guaymas (Gulf of California). Surface to 700 fathoms. 

 (From the open part of net.) Three specimens. 



