FISHERY BULLETIN: VOL. 83, NO. 1 



tubercles or occasionally with few on first abdomi- 

 nal somite. Carapace bearing patches of short 

 setae on dorsum, on pterygostomian and anterior 

 part of branchial regions, bordering branchiocar- 

 diac carina, and cluster immediately anteroven- 

 tral to hepatic spine; patches also present on 

 abdomen flanking dorsomedian carina and on 

 anteroventral part of pleuron of first three and 

 sixth somites. Abdomen lacking tubercles or with 

 few on first somite. 



Rostrum slender, usually somewhat decurved 

 but sometimes subhorizontal, occasionally with 

 anterior extremity upturned; moderately long, 

 overreaching distal margin of eye (extending as 

 far as basal 0.2 of second antennular article), its 

 length 0.30-0.43 cl, increasing linearly with 

 carapace length (Fig. 58); armed with three dorsal 

 teeth and two (rarely three) apical teeth, ventral 

 one considerably smaller than dorsal and usually 

 placed posterior to it but occasionally at same level 

 or even more anteriorly; first rostral tooth sub- 

 equal to, or slightly smaller than epigastric and 

 located opposite and anterior to level of orbital 

 margin, second tooth situated between 0.32 and 

 0.44 (mean 0.37) rl from orbital margin; and third 

 tooth betwen 0.58 and 0.80 (mean 0.66) rl. Strong 

 adrostral carina, parallel to and rather near ven- 

 tral margin, extending along entire length of ros- 

 trum. 



Carapace with postrostral carina low but robust 

 throughout its entire length in adults, weak in 

 juveniles, and bearing two teeth: 1) epigastric 

 tooth small, subequal to or barely larger than first 

 rostral tooth, situated anterior to but relatively 

 near level of hepatic spine, between 0.11 and 0.17 

 (mean 0.16) cl from orbital margin; and 2) pos- 

 terior tooth usually slightly, sometimes conspicu- 

 ously, larger than epigastric and placed well in 

 advance of posterior margin of carapace, between 

 0.57 and 0.65 (mean 0.63) cl from orbital margin. 

 Tuft of setae present immediately anterior to base 

 of each tooth. Antennal spine moderately long, 

 projecting from sharp, elongate buttress; hepatic 

 spine long, acutely pointed, arising from raised 

 area, and placed between 0.20 and 0.25 (mean 

 0.22) cl from orbital margin. Postocular sulcus 

 deep anteriorly, continuing posteriorly as long, 

 well-marked arched groove; hepatic sulcus sub- 

 horizontal; hepatic carina indistinct; branchio- 

 cardiac carina strong, longitudinally disposed 

 but curving dorsally near posterior margin of 

 carapace where also often sending short branch 

 ventrally. 



First article of antennular peduncle and gna- 



10 



20 30 40 



carapace length (mm) 



50 



Figure 58. — Sicyonia ingentis. Relationship between rostrum 

 length and carapace length (regression equation, >- = 0.75763 + 

 0.33933X). 



thai appendages, except third maxilliped, illus- 

 trated in Figure 4. 



Antennular peduncle with stylocerite produced 

 in long, sharp spine, its length 0.85-0.95 distance 

 between lateral base of first antennular article and 

 mesial base of distolateral spine; latter reaching 

 as far as midlength of second antennular article; 

 antennular flagella relatively long, mesial one, 

 about 0.4 as long as carapace, longer and more 

 slender than lateral; latter about 0.30 as long as 

 carapace. 



Scaphocerite overreaching antennular peduncle 

 by as much as 0.2 of its own length; lateral rib 

 produced distally in long, acute spine considerably 

 surpassing margin of lamella. Antennal flagellum 

 about 2 times as long as carapace. 



Third maxilliped about as slender as pereopods. 

 Basis and ischium of first pereopod unarmed. 



Abdomen with dorsomedian carina extending 

 from first through sixth somites, carina on first 

 very low and produced in small, stubby, anterior 

 tooth, smaller or only slightly larger than pos- 

 terior tooth on carapace; carina on first five 

 somites sloping posteriorly, on sixth produced in 

 large acute posterior tooth. 



Anteroventral margin of pleuron of first abdom- 

 inal somite slightly convex, sometimes straight in 

 juveniles; posteroventral margin, similar to that of 

 second and usually third somites, gently curved. 

 Anteroventral extremity of pleuron of first four 

 somites lacking spine, although that of second and 



70 



