- i9 - 



produced into a small, acuminate process or slender 

 tooth ; the lower margin of the carapace has an angle and 

 in still smaller specimens a denticle as in the young of 

 N. Couchi. I think that in young specimens of all species 

 the frontal plate is shaped nearly as in N. Couchi or 

 N. simplex, while it is triangular in subadult and adult 

 specimens of all species of the genus. 



Only 2 valid species have been established, viz. N. Cou- 

 chi Bell and N. australis G. O. S. ; here 2 new species 

 are added. The following diagnoses may be sufficient for 

 the recognition of all 4 species. Adult males are gene- 

 rally larger than the females. 



a. Lobe from first antennular joint somewhat small, 

 broader than long, triangular, with the acute end 

 situated above the inner margin of the antennula. 



Nyctiphanes Couchi Bell. — Female : Second anten- 

 nular joint with a rather large, oblong plate anteriorly 

 terminating in a spine, frequently digitate along its upper 

 margin and situated at the upper inner edge of the joint 

 near its end. Male : Second antennular joint with a low, 

 oblong plate without processes placed at the upper inner 

 edge of the joint a little from its end ; third joint with a 

 close row of generally 3 (3-5) spiniform, strong, partly 

 plumose setae on the inner side of the joint near its base. 

 Median lobe of the copulatory organs reaching rather near 

 the end of the lateral process. — Length generally 14-1 y mm . 



Eastern part of North Atlantic. 



N. capensis n. sp. — Female : Second antennular joint 

 with the upper inner margin terminating in a minute or 

 quite rudimentary spine, but without any protruding plate. 

 Male : Second antennular joint without any plate at the 

 end of the upper inner edge ; third joint with the close 

 row of nearly spiniform setae placed somewhat from the 

 base or at the middle of the inner side of the joint. Median 

 lobe of the copulatory organs reaching scarcely the middle 



(210) 



