FISHERY BULLETIN: VOL. 75, NO. 2 



propodus, and as much as 0.4 that of carpus. 

 Fourth pereopod reaching beyond antennular pe- 

 duncle by length of last three podomeres. Fifth 

 pereopod exceeding antennular peduncle by 

 length of last three podomeres or by latter and 

 as much as 0.1 length of merus. Pereopods increas- 

 ing in length from first to fifth. First pereopod 

 with rather inconspicuous spine on basis, and 

 either slender spine or no spine on ischium; second 

 pereopod with small spine on basis. In female, 

 coxa of third pereopod produced into large sub- 

 trapezoidal plate directed mesially, and bearing 

 minute anteromesial spine in juveniles. In both 

 sexes spine present on anteromesial corner of coxa 

 of fifth pereopod, considerably stronger in males 

 than in females, spine minute in latter and borne 

 on rounded coxal plate. 



Abdomen with middorsal carina from fourth 

 through sixth somites, posterodorsal margin of 

 fourth and fifth with short median incision; sixth 

 somite about 1.8 times as long as high, bearing 

 small, sharp spine at posterior end of carina, and 

 pair of minute spines posteroventrally. Telson 

 with rather shallow median sulcus practically dis- 

 appearing before reaching level of base of lateral 

 spines; sulcus flanked by ridges, blunt anteriorly, 

 sharp and slender posteriorly; terminal portion 

 length 5-6 times basal width; lateral spines length 

 1.5-2.0 times basal width of terminal portion. 

 Mesial ramus of uropod falling short of apex of 

 telson or slightly overreaching it; lateral ramus 



overreaching mesial ramus by as much as 0.25 of 

 its own length, and armed with slender, disto- 

 lateral spine, reaching as far as contiguous 

 margin of ramus. 



Petasma (Figures 2, 6A, B) with row of cincin- 

 nuli (hooklike structures along mesial margin of 

 median lobes of petasma that serve to interlock 

 its two halves) occupying only proximal 0.3 of 

 median line, and entire terminal margin armed 

 with spines; ventromedian lobule deeply cleft dis- 

 tally forming two elongate processes: mesial one 

 subspatulate and armed with rather conspicuous 

 spines mesially and minute ones distolaterally; 

 lateral process subelliptical, raised inwardly in 

 elongate prominence, and produced proximally in 

 small auricular process lacking spinules; distal 

 flap of ventrolateral lobule extending only to 

 basal portion of lateral process, and turned 

 strongly outward; ventral costa forming low prom- 

 inence at base of, and imperceptibly merging 

 with, flap. 



Appendix masculina (Figure 6C, D) elevated in 

 sharp mesial ridge and with proximal part pro- 

 duced laterally into rounded, flattened lobe; distal 

 part narrowing and bearing lateral row of setae 

 terminating in apical tuft of longer ones. Appen- 

 dix interna elongate ovate, extending almost as 

 far as appendix masculina, and also armed with 

 apical tuft of setae. Ventrolateral spur of basal 

 sclerite long, its length 0.7-0.8 that of appendix 

 masculina. 



FIGURE 6. — Hymenopenaeus debilis, 6 13 mm cl, off Cape Kennedy, Fla. A, Petasma, dorsolateral view of left half. 

 B, Ventral view. C, Right appendices masculina and interna, dorsolateral view. D, Ventral view. 



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