150 ANNALS OF SCOTTISH NATURAL HISTORY 



provided with numerous setae ; the proportional length of 

 the joints are nearly as shown by the annexed formula : — 



5-5- 2 -7'6-5-6 , 

 1234567 



Posterior antennae four-jointed ; the first and second joints are 

 elongate, the third and fourth very short (Fig. 3). Mandible 

 short and moderately stout, armed at the extremity with 

 two processes and two spiniform setae ; one of the processes 

 is conical and tooth-like, and serrate on the inner edge, the 

 other is somewhat cylindrical, and rounded at the end — the 

 margin that is opposed to the tooth-like process, and also 

 the end, being hispid (Fig. 4). Maxillae stout, broad, and 

 bearing a number of terminal spiniform setae. Anterior foot- 

 jaws stout, with a proportionally large marginal setiferous 

 lobe, and several terminal spines (Fig. 5). Posterior foot-jaws 

 two-jointed, those of the male armed with a strong, uncinate, 

 and sinuous terminal claw, which is considerably longer than 

 the stout broad joint from the end of which it springs, and 

 with which it forms a powerful grasping organ. At the base 

 of the claw, on the inside, there is a stout, short, and blunt 

 spine. The inner edge of the last joint of the foot-jaw is fur- 

 nished with a double (? or treble) row of elongate blunt- 

 pointed teeth. Two long stout plumose setae spring from the 

 inner margin, and near the distal end of the first joint. The 

 terminal claw probably passes down between these two setae, 

 and forms with them an interlocking apparatus (Fig. 7). 

 The posterior foot-jaws in the female, are also moderately 

 stout, but the terminal claw is feeble ; the last joint is not so 

 broad, and its inner margin bears two setiferous spines instead 

 of the double row of teeth possessed by that of the male. 

 The first, second, third, and fourth pairs of swimming-feet 

 are nearly alike ; both branches are short (the outer being 

 rather shorter than the inner) and three-jointed. The outer 

 branch is armed exteriorly with a number of dagger-like 

 spines, as shown in the figures (Figs. 8 and 9). The inner 

 distal angle of the first basal joint of all the four pairs bears 

 a spiniform seta. The inner distal angle of the second basal 

 joint of the first pair bears also an elongate dagger-like spine, 

 while a moderately long and stout seta springs from the 

 outer margin of the same joint. The fifth pair of feet are 



