pace. Adrostral sulcus deep, broad ijosteriorly, % 

 to 11/^ width of postrostral carina, measured at 

 level of one-eighth distance from its posterior end 

 to epigastric tooth, and long, ending %3 to 140 c-1- 

 from posterior margin of carapace. Adrostral 

 carina prominent, sharji along carapace, and long, 

 same length as adrostral sulcus. 

 CARAPACE (fig. 21) 



Length in proportion to total length smaller 

 in juveniles, accoi'ding to my data increasing 

 slightly at subadult stage. Gastrofrontal sulcus 

 broad, extending to about one-fifth c.l. ; gastro- 

 frontal carina sharp, turning slightly toward dor- 

 sal margin j)osteriorly, ending in acute orbital 

 angle anteriorly. Orbito-antennal sulcus wide 

 anteriorly, narrowing jjosteriorly to below apex of 

 hepatic spine. Gastro-orbital carina high and 

 sharp, occupying approximately posterior four- 

 fifths of distance between postorbital mai'gin and 

 hepatic spine. Antennal carina very prominent. 

 Cervical sulcus 1/5 to i/4 c.l., ending slightly an- 

 terior to midlengtJi of carapace. Hepatic carina 

 Vs ^ % <'-l-5 sharp, sloping slightly anteroventrally 

 to end 1/13 to 1/20 ""-l- from anterior margin of cara- 

 pace. Antemaal spine prominent and acute ; hepatic 

 spine pronounced. 



ANTENNULES 



Lateral flagellum I/2 to % length antemiular 

 peduncle, slightly longer than median flagellum 

 and with articles shorter than those of median 

 flagelliun. Anterolateral spine small, sharp. Stylo- 

 cerite acuminate, reaching slightly beyond mid- 

 length of first antennular segment. Prosartema 

 extending to distal end of proximal fifth of second 

 antennular segment. 



ANTENNAE 



Length of scaphocerite 21^ times maximum 

 width, its length relative to carapace length de- 

 creasing slightly with growth; spine reaching at 

 least distal end of antennular peduncle and at 

 most distal end of pi-oximal one-fourth of thick- 

 ened portion of lateral flagellum. Carpocerite 

 length 114 width, reaching distal end of optic 

 peduncle. Antennal flagellum relatively short, 

 about lYs lx)dy length. 



THORACIC APPENDAGES 



Third maxilliped reaching at least proxunal 

 one-fifth but not beyond distal end of second 

 antennular segment ; length of dactyl % to % that 

 of propodus. First pereopod reaching base of car- 

 pocerite and at most exceeding it by seven-eighths 



Figure 21. — Penaeiis (M.) duorarum 

 tluorarum Burkenroad. Cephalo- 

 thorax, ? 37.5 mm. c.l., off Mel- 

 bourne Beach, Fla. 



504 



U.S. FISH AND WILDLIFE SERVICE 



