344 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxm. 



SUMMARY. 



The life history of the genera belonging to this subfamily is similar 

 to that of the Caliginse and Euryphorinae except in the following 

 particulars : 



(1) The pigment which develops in the nauplii takes the form of a 

 large central mass rather than scattered spots, and is often so dense 

 as to appear almost black. 



(2) The balancers are slender and cylindrical, as in the Eury- 

 phorinse, but they are attached nearer to the posterior end of the 

 body of the nauplius, and point backward at an angle of about 45° 

 to the central axis. 



(3) In the metanauplii\s the first thorax segment is fused with the 

 carapace as in the Euryphorinae, but the first antennae are like those 

 of the adult and not dichotomously branched, nor even armed with 

 long plumose setge. The rami of the second maxillae are fused and 

 each consists of a stout basal joint tipped with a single spine. The 

 swimming legs are laminate, but the separate joints are long and 

 narrow, and they reach far back on the ventral surface. 



(4) The chalimi are attached by frontal filaments, not single and 

 cylindrical as in the Caliginae, but double, each strand broad and 

 ribbon-like, the two strands stanchng side by side and only long, 

 enough to reach the fish's skin, and allow the frontal margin of the 

 chalimus's carapace to swing clear of it. These filaments have no 

 enlargements at their bases like those seen in the Caliginae, but are 

 of uniform width throughout. The frontal glands developing these 

 filaments are quadruple instead of double. 



(5) The body form of the young female chalimus is almost exactly 

 the same as that of the adult Nogaus male, the carapace having 

 elongate posterior lobes, the free thorax segments being entirely dis- 

 tinct and almost uncovered by the dorsal plates, and the abdomen 

 projecting its entire length behind the genital segment. We thus 

 have visible and convincing proof of the relationship of the two 

 sexes, and also of the fact that the female degenerates after becom- 

 ing fixed. 



(6) The appendages of the young chalimus are almost exactly like 

 those of the adult; the second maxillipeds have not yet attained 

 their proportionate size, but are small and the terminal joint is folded 

 over against the basal joint. 



(7) In subsequent development the posterior lobes of the carapace 

 are shortened, the free thorax segments are telescoped together, and 

 the dorsal plates are developed to cover them; the genital segment 

 is increased in size, often becoming larger than the carapace, and in 

 this increase it grows gradually back over the abdomen, so that the 

 latter comes to lie on the ventral surface of the former, and is com- 

 pletely concealed in dorsal view. 



