FISHERY BULLETIN: VOL. 83, NO. 1 



Figure 35. — Sicyonia affinis Faxon, ? 17 mm cl, 4.4 km off Isla Manuelita, Costa Rica. Lateral view. Scale = 5 mm. 



slightly anterior to level of hepatic spine at about 

 0.15 cl from orbital margin, small, subequal to, or 

 only slightly larger than first rostral tooth; and 

 large posterior tooth, considerably larger than 

 epigastric, hooklike, with apical portion acutely 

 pointed and slightly curved anteriorly; tooth 

 placed distinctly in advance of posterior margin of 

 carapace, betw^een 0.65 and 0.75 (mean 0.67) cl 

 from orbital margin. Postrostral carina low an- 

 teriorly forming high crest descending gently from 

 posterior tooth to posterior margin of carapace. 

 Tuft of setae present at anterior base of each tooth. 

 Antennal spine small, sharp, projecting from 

 weakly developed buttress; hepatic spine moder- 

 ately long and acutely pointed, situated at 0.20- 

 0.25 (mean 0.22) cl from orbital margin; hepatic 

 sulcus almost horizontal, accompanying incon- 

 spicuous carina; branchiocardiac carina broad, 

 low, longitudinally disposed except for posterior 

 part curving dorsally near posterior margin of 

 carapace. 



Antennular peduncle with stylocerite long, al- 

 most reaching level of mesial base of distolateral 

 spine, its length about 0.95 distance between lat- 

 eral base of first antennular article and mesial 

 base of distolateral spine; latter reaching as far as 

 distal 0.25 of second antennular article, antennu- 

 lar flagella short, mesial one more slender and 

 longer, about 0.20 cl, than lateral, 0.16 cl. 



Scaphocerite extending to distal end or slightly 

 overreaching antennular peduncle; lateral rib 

 produced distally in long, strong spine, surpassing 

 margin of lamella. Antennal flagellum incomplete 

 in specimens examined. 



Third maxilliped stouter than pereopods. Basis 

 and ischium of first pereopod unarmed. 



Abdomen with strongly marked dorsomedian 

 carina extending from first through sixth somites, 

 carina on first somite produced anteriorly in 

 strong tooth (slightly more elevated than posterior 

 tooth on carapace), its anterior margin subvertical 

 but apical extremity slightly curved anteriorly; 

 carina deeply cleft posteriorly on first five somites, 

 on fourth and fifth not truncate but sloping gradu- 

 ally to apex of cleft, and on that of sixth somite 

 produced in large, acute, posterior tooth. 



First four somites with rounded or broadly an- 

 gular anteroventral extremity unarmed; fourth 

 somite with posteroventral extremity rounded and 

 lacking spine, and that of fifth and sixth somites 

 bearing minute spine. 



First somite marked with short, weak, an- 

 teromedian pleural sulcus, its length slightly <0.2 

 distance from origin (emargination on anterior 

 margin) to ventral margin of pleuron; united pos- 

 terior tergal-posteromedian sulci relatively shal- 

 low. Second and third somites with weak anterior 

 and posterior tergal sulci joining anterodorsally; 



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