distinct ventrally; dark chromatophoi-es scattered 

 throughout and when expanded giving animal a 

 grayish cast ; tips of rostrum and flagella reddish ; 

 legs pinkish or yellowish orange; pleopods and 

 uropods yellowish at base, pink distally; telson 

 and sixth abdominal segment sometimes pink 

 (Holthuis, 1959). 



Habitat. — This species lives in a narrow zone 

 along shore, and at times in the lower portion of 

 estuaries (Gunter, 1950; Holthuis, 1959), from 

 2.5 to 20 fathoms, rarely to 24 fathoms (Burken- 

 road, 1939; Gunter, 1950). 



Type locality. — Rio de Janeiro, Brazil. 



Known range. — Between Capes Hatteras and 

 Lookout, N.C., through Gulf of Mexico and 

 Caribbean Sea to near Santos, Sao Paulo, Brazil ; 

 Pacific coast variety (X. riveti, see Burkenroad, 

 1934b) from Mexico to northern Peru. 



Remarks. — This species is of commercial im- 

 portance in the southern United States (Wey- 

 mouth, Lindner, and Anderson, 1933 ; Hildebrand, 

 1954), and of great importance in South America 

 (Lindner, 1957; Higman, 1959), especially along 

 the northeast coast where it dominates the near- 

 shore fishery and the young dominate the coastal 

 nursery areas, perhaps offering serious competi- 

 tion to other penaeids. 



No detailed study of the ecology of this species 

 has been made. Burkenroad (1949) observed ripe 

 or nearly ripe females off North Carolina in May, 

 and Gunter (1950) found them along the Texas 

 coast in June. Vieira (1947), in a study on 

 maturation, found mature females off Sao Paulo, 

 Brazil, from November to January. 



Gunter (1950) studied a population ranging in 

 size from 28 to 127 mm. total length. He found 

 a population mode of 38 mm. total length in 

 October but no definite modes in other months. 

 The species was most abundant in fall. Gunter 

 pointed out that the species does not customarily 

 live in bays, even though it lives in shallow 

 water close to the Texas shore. The young may 

 enter the lower end of Texas bays (21.2-30.7 

 °/ 00 ), but most individuals were found in the 

 Gulf of Mexico in a salinity range of 29.7 to 

 35.2°/ 0o . Similar salinity tolerances were implied 

 by Lindner (1957) and noted by Holthuis (1959). 

 Though the South American shrimp are caught in 

 estuaries and rivers, the penetration into these 

 areas is greatest in dry seasons. Both Lindner 



and Holthuis gave data on the fisheries and proc- 

 essing methods. 



Genus Trachypeneus Alcock, 1901 



Burkenroad, 1934b, p. 94. 



Trachypeneus constrictus (Stimpson) 



Figure 21 



Penaeus constrictus Stimpson, 1871b, p. 135. 

 Trachypeneus constrictus: Hay and Shore, 1918, p. 378, pi. 

 25, fig. 9.— Schmitt, 1935a, p. 131. 



Recognition characters. — Dorsal region of cara- 

 pace with fine, short, appressed setae; branchial 

 region of carapace and last two abdominal seg- 

 ments variably pubescent ; abdomen smooth proxi- 

 mally. Carapace carinate except for short stretch 

 near posterior border; a spine behind base of 

 rostrum; antennal and hepatic spines well de- 

 veloped; a rectangular toothlike eminence at 

 orbital angle; lateral groove extending about 

 three-fifths length of carapace; anterolateral 

 angle truncate. Rostrum reaching to about mid- 

 dle of second segment of antennal peduncle, 

 directed slightly upward; upper margin usually 

 slightly arched and bearing usually seven to nine 

 equidistant teeth diminishing in size toward tip. 

 Eyes large, reniform. Antennular peduncle pubes- 

 cent above, extending slightly beyond antennal 

 scale; flagella shorter than carapace. Third 

 maxilliped, first and second legs with basal spines. 



Abdomen carinate from fourth to sixth segment. 

 Telson with two rounded carinae above ; tapering 

 to a short acuminate tip, armed on either side with 

 a short spine. 



Figure 21. — Trachypeneus constrictus (Stimpson). Ani- 

 mal in lateral view, approximately X 1.5 (after Verrill, 

 1922). 



MARINE DECAPOD CRUSTACEANS OF THE CAROLINAS 



31 



