Figure 14. — Penaeiis (L.) sc/i miffiBurkenroad. Rostrum, 9 39mm. c.l., Santos, Brazil. 



Postrostral carina narrow and relatively short, 

 ending i/^ to 143 c.l. from posterior margin of 

 carapace, shorter in larger individuals. Median 

 sulcus shallow, sometimes extremely so, inter- 

 rupted, often appearing as two elongated depres- 

 sions followed posteriorly by series of three to six 

 minute pits. Adrostral carma rounded and short, 

 ending at level of epigastric tooth. Adrostral sul- 

 cus shallow, and short, same length as adrostral 

 carina. 

 CARAPACE (fig. 15) 



Length in proportion to total length smaller in 

 juveniles, according to my data increasing sud- 

 denly at about the size at which subadult stage is 

 reached. Gastrofrontal sulcus and carina absent, 

 except for a short, almost imperceptible rib sub- 

 parallel to first two rostral teeth. Orbito-antennal 

 sulcus wide anteriorly and narrowing posteriorly 

 to below apex of hepatic spine, there widening 

 into base of spine. Gastro-orbital carina pro- 

 nounced, sharp and relati^•ely short, occupying 

 Ijosterior % to % distance between postorbital 

 margin of carapace and hepatic spine. Antennal 

 carina very prominent. Cervical sulcus deeper at 

 its lower half and extremely shallow above, end- 

 ing at about two-fifths c.l. from postorbital margin 

 of carapace. Hepatic carina % to 14 c.l., sharp, 

 sloping slightly anteroventrally to end Vn to W^ 

 c.l. from anterior margin of carajDace. Antennal 

 spine acute and relatively short; hepatic spine 

 prominent. 



ANTENNULES 



Lateral flagellum long, its length seven-tenths to 

 almost same lengih as antennular peduncle, 

 slightly longer than median flagellum, with arti- 

 cles shorter than those of median flagellum. Median 

 flagellum exhibiting sexual dimorphism : in adult 

 males markedly flattened dorsoventrally, with two 

 closely set rows of stout processes of unequal sizes 

 along midportion of internal margin, and with 

 long setae along proximal one-fifth of external 

 margin ; in females processes lacking but long setae 

 present along proximal two-fifths of external mar- 

 gin. Anterolateral spine small, sharp. Stylocerite 

 reaching slightly beyond midlength of first anten- 

 nular segment. Prosartema extending to proximal 

 fifth of second antennular segment. 

 ANTENNAE 



Scaphocerite 21/0 to 2% times maximum width; 

 spine reaching three-quarters of length of third 

 antennular segment to one-fifth of length of thick- 

 ened portion of antennular flagellum. Carpocerite 

 about 114 times longer than wide, its distal end 

 reaching base of eye. Antennal flagellum very long, 

 21/2 to 22/3 times body length. 

 THORACIC APPENDAGES 



Tliird maxilliped reacliing at least distal end of 

 proximal five-sixths of first antennular segment, 

 and at most distal end of proximal five-sixths of 

 second antennular segment ; length of dactyl % to 

 % of propodus. First pereopod extending to distal 



490 



U.S. FISH AND WILDLIFE SERVICE 



