156 PROCEEDINGS OF THE NATIONAL MUSEUM vol. los 



ments subequal in length, the second narrowed. Outer spine of 

 segment 1 with serrate flange, reaching to end of segment 2. First 

 outer spine of segment 2 similar in size and armature to that of seg- 

 ment 1, second outer spine about half length of first; both spines 

 reach beyond end of exopod. Apical part of segment 2 modified, 

 an unperfectly separated, rounded serrate lappet on the inner margin 

 opposite the placement of the second outer spine; beyond this lappet, 

 the segment slightly incised on the anterior side (the possibility that 

 this tip is at least partially movable is suggested by the various 

 positions found in different dissections; the tip may or may not be 

 interpretable as an unperfectly separated third segment). 



Left exopod: Segment 2 much stouter than segment 1, broadened 

 and stout at its apex into which is set the highly modified third seg- 

 ment; its outer distal spine narrowed and tapered, reaching beyond 

 the tips of the processes of the third segment, armed only with outer 

 marginal spinules. Third segment consisting of a shortened seg- 

 mental portion clearly separated on the anterior side from the second 

 segment (fig. 24) but imperfectly separated on the posteromedial 

 side. The segmental portion of the surface of the anterior side 

 deepl}^ incised medially with heavy marginal sclerotizations and form- 

 ing in part on its posterior side the base for the attachment of a set 

 of thin, apically and irregularly fragmented membranes (or a single 

 folded membrane) and thi*ee heavier, exceedingly flexible processes. 

 Of these, the innermost simple in structure (setiform). One process, 

 with an irregularly serrate, flared tip, has a broadened base which is 

 set into a socket of the posteromedial portion of the segment (fig. 25). 

 The other process is deeply widened at its base and attached inside 

 the segment on the anterior side (fig. 24), below its attachment it is 

 abruptly contracted into a long narrow setiform process with a 

 slightly widened tip which is split near its end. These processes 

 appeared in dissections separated as shown in figure 25, or twined 

 around one another as in figure 24. 



In interpreting the figures given here, it must be remembered that 

 the membranes, though perhaps representing only one single struc- 

 tm'e, are u-regularly fragmented and folded, and their appearance 

 in any one dissection may be different from anj'^ other dissection. In 

 figure 24, the membrane shown is only the expanded outer portion of 

 that shown in figm-e 25; the edge appeared in all dissections to be 

 strengthened by a heavy band. 



Right cndopod elongate-narrow, reaching to near end of exopod, the 

 tip partially split; anterior side set basally with groups of surface 

 spinules (fig. 26). Left endopod short, reaching only little beyond 

 exopod segment 1; inner margin with two movable processes; the 



