NO. 1368. 



DESCRIPTIONS OF ARGULIDJi>- WILSON. 



647 



the hooks upon the basal joint of the first pair are lar^-e and powerful, 

 while the spines are ver}' long- and sharp. The two tcrniiiiul joints 

 carry numerous setaj, but do not project much beyond the lateral 

 hook (fig-. 24:). The second antenna' are -l-jointed. the ba.sal joint 

 having- a long- spine on its posterior margin, while each of the 

 remaining- joints has a tuft of stout setee at its distal end. The eyes 

 are large, somewhat lunate, and inclined toward the longitudinal ribs; 

 the facets are small and numerous and crowded closely together. 



On the median line between the eyes 

 and posterior to the large spines w^hich 

 arm the base of the second antennas 

 there is a groove for the reception of 

 the stylet (fig. 25). It extends back as 

 far as the base of the proboscis, and 

 is lined on either side with a heavily 

 corrugated layer of chitin. 



The mouth difl'ers considerably from 

 that of other described species, and 

 presents a peculiar appearance )w rea- 

 son of the arrangement of its chitin 

 framework. The mouth opening is 

 narrowed antero-posteriorly and elon- 

 gated sidewise so as to appear like a 

 narrow transverse slit, broken at the 

 center by the protruding under lip 

 (fig. 2H). On examining- the chitin 

 skeleton, we find the same four longi- 

 tudinal ribs connected at the latitude 

 of the mouth by a transverse frame- 

 work. But the structure and arrange- 

 ment of this latter is very different 

 from anything yet described, as can 

 be readily seen in fig. 26. The most 

 noticeable differences are the elliptical 

 loops on either side of the mouth and 

 a trapezoidal projection which extends 

 down into the center of the upper lip 

 to the very edge of the mouth opening. 



The transver.se rib also, which is situated at the junction of the upper 

 and under lips on either side, turns outward at the joint nearest the 

 mouth and protrudes like a knob through the side of th(> probo.scis. 

 The rudimentary palp along-side this joint is very small. Inside the 

 lips may be seen a part of the long, sickle-shaped mandibK>s. edged with 

 sharp saw teeth. The maxilhe have not yet been seen. 



The anterior maxillipeds are large, well separated, and i)lace<l far 

 forward close to the maroin of the antero-lateral siinises. The nuMU- 



e.in. 



c h.r. 



Ho. 25. — Sting and poison gland ok argu- 



LUS VERSICOLOR, ch.r., CHITIN RIB OF PRO- 

 BOSCIS; (/., DrCTS OF POISON GLAND; <7., 



POISON gland; m.m., mandible mvscles; 

 oe.m., lEsoPHAGUS mvscle; 01:111.', side 

 muscle of cesophagus; r.jM., retractor 



muscle; X.. STING. 



