COPEPODA FROM IFALUK ATOLL 95 



scarcely can suppose, however, that A. Scott overlooked the very 

 characteristic spinulose internal seta on the baso-endopodite; part of 

 the differences mentioned above may be due to incorrectnesses in A. 

 Scott's drawings, faults of preparation, or, as far as the maxillipede 

 is concerned, angle of vision. 



The present specimens are all from weed washings off the edge of 

 the elang, south of Elangalap, Ifaluk Atoll, in 3 to 4 feet of water. 

 The specific name confusus has been suggested by their confusing 

 resemblance to H. trisetosus Lang. 



Genus Perissocope Brady, 1910 



The discovery of the male of a new species of Perissocope, to be 

 described below, makes it possible to give a more complete diagnosis 

 of this genus. 



Generic diagnosis. — Body in dorsal aspect elongated, frontal part 

 rounded, cephalic somite smooth or longitudinally carinated, rostrum 

 squarish plate with broadly rounded apex, distinctly visible in dorsal 

 aspect, directed forward and shghtly downward. Body fairly strongly 

 compressed dorsoventrally, gradually tapering posteriorly, epimeral 

 plates well developed, produced laterocaudally, without sharp divi- 

 sion between cephalothorax and abdomen, head and 1st thoracic 

 somite fused. 



Females with 8- or 9-segmented antennules, basal 4 segments long, 

 apical 4 or 5 segments short. Antenna with allobasis, endopodite 1- 

 segmented, with 8 setae and spines, exopodite 2-segmented, with 

 2+2 setae. Exopodite and endopodite of mandible unsegmented, 

 small. Structure of maxillule imknown. Maxilla with 3 endites and 

 unsegmented endopodite. Maxillipede chelate, coxa of moderate 

 length, basis slightly swollen and endopodite unsegmented. 



Leg 1 with 3-segmented exopodite and 2-segmented endopodite, 

 coxa and basis well developed. 1st exopodal segment well developed, 

 2nd segment styhform, twice as long as 1st, both with external seta. 

 3rd exopodal segment short with 4 claws. 1st endopodal segment 

 long, reaching about half 2nd exopodal segment, with strong internal 

 seta at upper portion of external margin. 2nd endopodal segment 

 small, with 2 claws. 



Legs 2 to 4 with 3-segmented exopodites and endopodites, setation 

 as represented in setal formula on page 100; 3rd exopodal segment of 

 legs 2 and 3 with 3 spines at external margin, 3rd exopodal segment 

 of 4th leg with 2 or 3 external marginal spines. 



Leg 5 with distinct, ovate exopodite, bearing 5 to 7 setae or setiform 

 spines. Baso-endopodite with at least 5 setae, well developed; ex- 

 ternal lobe small, with fine seta. 



