FISHERY BULLETIN: VOL. 75, NO. 2 



third in line with orbital margin. Adrostral carina 

 low and sharp, extending from orbital margin 

 almost to apex of rostrum; orbital margin project- 

 ing in narrow shelf. Postrostral carina strong to 

 near posterior margin of carapace, followed by 

 small tubercle. Pterygostomian spine slender and 

 sharp like other lateral spines on carapace; post- 

 orb'tal (situated directly posterior to antennal), 

 pterygostomian, and branchiostegal spines with 

 sharp basal carina, that continuous with branchi- 

 ostegal spine merging with hepatic carina. Cer- 

 vical carina strong, extending to, but not crossing, 

 postrostral carina, its dorsal extremity located 

 immediately posterior to midlength of carapace; 

 hepatic carina blunt, its accompanying sulcus 

 deep; additional short carina lying dorsal and 

 parallel to posterior part of hepatic sulcus; post- 

 hepatic carina long, running from posterior 

 extremity of hepatic sulcus to posterior margin 

 of carapace; branchiocardiac carina also long, 

 reaching posterior margin of carapace; short 

 sulcus extending posterodorsally from near pos- 

 terior end of branchiocardiac carina; submarginal 

 carina well defined, extending along entire length 

 of branchiostegite. 



Eye as illustrated (Figure 18A). 



Antennular peduncle length equivalent to 

 about 0.4 that of carapace; prosartema extending 

 to distal margin of eye, but falling short of distal 

 end of first antennular article; stylocerite short, 

 extending 0.5 of distance between its proximal 

 extremity and mesial base of distolateral spine; 

 latter rather long, slender, and sharp. Antennular 

 flagella incomplete in specimens examined. 



FIGURE 18. — Eyes. A, Hymenopenaeus doris, syntype 9 32.5 

 mm cl, off Cabo Velas, Costa Rica. B, Hymenopenaeus nereus, 

 syntype 9 21.5 mm cl, south of Cabo Blanco, Costa Rica. 



Scaphocerite overreaching antennular peduncle 

 by 0.25 of its own length; lateral rib ending in 

 slender spine, extending to distal margin of 

 lamella. Antennal flagellum broken in specimens 

 studied. Mandibular palp reaching distal 0.2 of 

 carpocerite; proximal article about 2.5 times as 

 long as wide; distal article considerably shorter 

 and narrower than proximal, and tapering to 

 blunt tip. First maxilliped with single rudi- 

 mentary arthrobranchia at base. Third maxilli- 

 ped reaching beyond antennular peduncle by 

 dactyl and almost entire length of propodus; 

 length of dactyl about 0.65 that of propodus. 



First pereopod extending to distal end of carpo- 

 cerite. Second pereopod overreaching antennular 

 peduncle by length of propodus. Third pereopod 

 exceeding antennular peduncle by length of pro- 

 podus and about 0.33 that of carpus. Fourth pereo- 

 pod overreaching antennular peduncle by dactyl, 

 propodus, and almost entire length of carpus. 

 Fifth pereopod reaching beyond antennular pe- 

 duncle by length of distal three podomeres. Pereo- 

 pods increasing in length from first to fifth. First 

 pereopod with rather inconspicuous spine on 

 basis, and slender spine on ischium; second pereo- 

 pod with minute spine on basis. In female, coxa of 

 third pereopod produced into large, subtrapezoidal 

 plate, broadest mesially, and disposed almost at 

 right angle to podomere; coxa of fifth pereopod 

 armed with minute anteromesial tooth. 



Abdomen with middorsal keel from fourth 

 through sixth somites, and strong longitudinal 

 rib along lateral surface of fourth and fifth 

 somites; posterodorsal margin of latter two 

 somites with short median incision; sixth somite 

 very elongate, 2.5 times as long as high, bearing 

 small, sharp spine at posterior end of keel and 

 pair of minute posteroventral spines. Telson with 

 broad median sulcus deep anteriorly, quite shal- 

 low posteriorly, and flanked by low, sharp ridges; 

 terminal portion length 5-6 times basal width; 

 lateral spines short, their length about 1.5 times 

 basal width of terminal portion. In only specimen 

 with complete uropod, mesial ramus falling short 

 of apex of telson; lateral ramus overreaching 

 mesial ramus by 0.2 of its own length, and armed 

 with small, terminal, distolateral spine. 



Petasma unknown; males not recorded. 



Thelycum (Figure 19A, B) with median protu- 

 berance on sternite XIV subpyramidal, with sub- 

 triangular base and apical portion strongly 

 produced into elongate, acute projection directed 

 ventrally or anteroventrally, and lying quite near 



284 



