20 c. BOVALLIUS, NOTES OX THE PTERYGOCERA ARENARIA. SLABBEIl. 



short, straight spine, and every notch two long plume-like 

 ciliated bristles. The pöste rior side of the joint is strongly 

 produced and carries along its whole margin long phimose 

 bristles. The hinder and lower margin of the produced part 

 of the joint is, moreover, armed with short, thick spines. The 

 whole outer side is also beset with similar spines, as is also 

 the foremost lower angle. The carpus is considerably shorter 

 than the meros, but has the same breadth; it is provided 

 with a transverse row of protuberances, armed with spines of 

 the same appearance as those of the preceding joint (Pl. III, 

 fig. 24); in the fore-margin it presents only one ciliated bristle. 

 The posterior part is strongly produced, of abont the same 

 breadth as the principal part of the joint, the lower margin 

 beset with plume-like ciliated bristles and some few straight 

 spines. The 2^'''opus is somewhat longer than the carpus but 

 much slenderer; its foremost margin is coarsely serrated and 

 armed with strong spines, and one or two short ciliated brist- 

 les. Its truucated extremity is beset with long, straight spi- 

 nes (Pl. III, fig. 20). The posterior margin is quite smooth 

 without bristles or spines. Of a dacti/lus there is no trace. 

 The foitrth pair of pereiopoda (Pl. Il, fig. 13) is the stron- 

 gest of all, and assists essentially in forming tlic armour, 

 which shelters the lower side of the body, whcn the animal 

 rests or is menaced by some danger. Its gill-bladder also is 

 longer and more firm than those of the other legs. The basis 

 is large, rectangular with rounded angles directed forwards 

 and not downwards, like that of the preceding pairs of legs. 

 The upper part is thick, filled with strong muscles, the lower 

 is thin, laminiform. The upper margin, feebly arched, is, as 

 well as the frontmargins of the following joints, elosely friu- 

 ged with long, plumelikc ciliated bristles, the loAver and po- 

 sterior börder carrying short and smooth bristles. llie ischium is 

 short, without bristles on the posterior margin. The meros is very 

 large, almost of the same size as the basis, its lower part is much 

 broader than the upper one. The upper half of the foremost 

 margin is feebly arched, the lower straight, strongly serrated, 

 with 3 — 4 coarse spines on Qyery tooth; moreover, as said 

 above, the fore-margin of the joint is close beset with long 

 plumelike bristles. Its lower margin is almost straight, close 

 beset with very long plumelike ciliated bristles and some 

 spines. The posterior margin is strongly arched, coarsely 



