22 c. BOVALLIUS, NOTES ON THE PTERYGOCERA AREXARTA, SLABBER. 



lower angles of the joint there are a greater number of siich 

 ones. The lower margin, almost straiglit, is close beset with 

 alternately long and short straight spines. The posterior 

 blunt corner 6f the expansion of the joint carries two far 

 greater, plumelike ciliated bristles (PJ. IV, fig. 63). The 

 upper margin is serrated, beset with spines and the just na- 

 med plumelike bristles. The outer side of the joint carries 

 near its upper börder four groups of slender, straight or fee- 

 bly bent spines of different length (Pl. II, fig. 15). The car-m 

 pus is almost triangulär, its foremargin is arched, coarsely 

 serrated, with 4 — 5 short, thick spines of different length, 

 some of which seem to be provided with an opening at the 

 point (Pl. III, fig. 27). The posterior margin is almost straight, 

 quite smooth. The p)ropus is somewhat big, broad in the 

 middlc, the breadth decreasing towards both ends, coarsely 

 serrated, beset with spines of the same form as those of the 

 preceding joints. There is no dactyliis. 



The three pairs of pleopoda (Pl. III, fig. 32) are all of the 

 same structure, the last one is the shortest. Each of them has 

 a short joint, immoveably attached to the median line of the seg- 

 ment; to this articulates the proper basal joint of the natatory 

 foot. This is short, thick and broad, expanded below. The 

 inner and outer margins are curved, the inner one carries two 

 strong, short spines, provided with a broad tooth just below 

 the point, and some few short, thick bristles, the outer one 

 sevcral long, ciliated bristles. On tlie anterior side of the 

 peduncle there are, morcover, sevcral somewhat long, flexible, 

 smooth bristles. From the middle of the loAver margin pro- 

 jects a taillikc buudlc of long, flexible, ciliated hairs. Ou 

 the lower side of the peduncle the two natatory branchcs are 

 affixed; the outer one, which is by far the longer, is attached 

 near tlie outer angle of the pcdviucle. the inner one a little 

 within the middle. The outer one is composcd of 20 — 23 

 joints; the inner one of 1-5 — 17; each joint carries tAvo swim- 

 ming-bristles, one at its outer angle and one at the inner, 

 lower angle. excepting the lirst joint, which is far longer 

 and broader than any of the other, and cvidently made up 

 of sevcral joints united; it carries on the side, directed 

 towards the second swinimlng-flagellum, two, on the other 

 side 10 — 11 swimming-bristles. The swimming-bristles (Pl. 

 IV, fig. 75) are jointed or, righter perhaps, composed of 



