102 U.S. NATIONAL MUSEUM BULLETIN 236 



abdomen better marked than in female. 1st and 2nd abdominal so- 

 mites separate, each of about same length as 3rd abdominal somite. 

 4th abdominal somite and anal somite of equal length, each shorter 

 than preceding somites. 



3. Antennules (fig. 32g) subchirocerate, longer than in female, 

 surpassing % length of cephalic somite. 5th segment swollen, with 

 distinct aesthetasc and 2 setae. Apical digit formed by 4 indistinctly 

 fused segments. I have represented the setation as well as possible 

 in figure 32^, but some of the setae are very minute and others may have 

 been overlooked. I failed to observe differences in the structure of 

 oral appendages or antennae. 



4. Legs 1 and 4 as in female, exopodites of legs 2 and 3 as in female, 

 but endopodites of these legs modified. Endopodite of leg 2 (figs. 32A., 

 33e) 3-segmented: segment 1 normally built, without setae; segment 

 2 with internal seta, end of internal margin drawn out to a point, 

 reaching half length of 3rd endopodal segment; latter segment elongate, 

 gradually tapering into bifid point. Two internal setae : fine proximal 

 seta and much thicker distal seta. Endopodite of leg 3 (fig. 33/) also 

 3-segmented. Segment 1 normal, with fine internal seta. Segment 

 2 with internal seta, external margin at apex running into short, curved 

 spine, apparently fitting into hollowed part of 3rd endopodal segment, 

 with 1 fine internal seta. Apical segment with total of 5 setae; more 

 external seta very fine and small. 



Leg 5 (fig. 32i) almost as in female, but with reduced number of 

 setae on baso-endopodite. Exopodite with same number of identically 

 developed setae. Baso-endopodite less produced, reaching only % 

 length of exopodite, with only 2 setae of unequal size. 



Remarks. — This new species, which clearly belongs to the genus 

 Perissocope, is closely related to P. littoralis Lang, from which it differs 

 in the armature of legs 2 to 4 and in the structure of leg 5. The 

 setal formula of those species of Perissocope that are adequately 

 known have been tabulated below: 



The present specimens were obtained from sand samples, collected 

 about 60 feet from the reef margin of the seaward side of Falarik in 

 the Ifaluk Atoll. The specific name has been chosen in honor of 

 Dr. Frederick M. Bayer, formerly Associate Curator, Division of 

 Marine Invertebrates, U.S. National Museum, Washington, D.C., 



