4 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 66 



The mandible, the maxilla, and the first maxilliped are much 

 reduced in the adult male. (pi. 3, figs. 16-18.) In immature 

 males which are only 0.1 to 0.2 millimeter shorter than the adults, 

 these mouth parts are like those of the female; this indicates that 

 the reduction takes place during the final moult in transforming to 

 an adult. Figure 16 shows that the masticatory part of the mandi- 

 ble is very weak and has only a small cutting edge. 



The second pair of maxillipeds and the first three pairs of swim- 

 ming legs of the male are like those of the female. The fourth pair 

 of legs of the male differs from that of the female in that the 

 first basal segment does not possess a spine on the inner margin, 

 but it has instead a small, cuplike depression about two-thirds of 

 the way toward the outer end. 



The fifth pair of legs of the male (pi. 3, fig. 20) is unusually 

 large, asymmetrical, and greatly modified for the transfer of the 

 spermatophores. The proximal third of the first basal segment is 

 fused. The second basal segment of the right leg is large, quad- 

 rangular, and about as long as broad. The inner ramus of the 

 right leg is elongated, reaching beyond the second segment of the 

 outer ramus, with the outer margin and the distal third hyaline. 

 The first segment of the outer ramus of the right leg is elongated, 

 subtriangular in outline, with a small spine on its outer margin. 

 A narrow hyaline lamella arises at the inner distal angle of this 

 segment and extends outward along the second segment and the 

 base of the terminal hook. The second segment of the outer ramus 

 is small and bears a small, inward-projecting spine at its oiiter 

 distal angle; it also bears a long terminal hook which is recurved 

 at the outer end. 



The second basal segment of the left leg is oblong, nearly twice 

 as long as broad. The inner ramus of this leg consists of a broad, 

 somewhat triangular basal portion, with a digitiform process at 

 the outer distal angle; the outer margin and the fingerlike process 

 are hyaline. The second segment of the outer ramus of the left 

 leg is larger than the first and possesses a protuberance at the 

 inner proximal angle; the second segment terminates in a conical | 

 process, with a small spine at the base of this process. ' 



Length of adult male, 2.45 to 2.55 millimeters. 



The fifth pair of legs of an immature male 2.35 millimeters long 

 is shown in plate 3, figure 19. These appendages are still com- 

 paratively simple when this stage is reached, the chief modification 

 taking place between this and the adult stage. The first antenna 

 of an immature male of this size is like that of the female, with 

 seven sensory appendages and with the eighth and ninth segments 



