DECAPOD CRUSTACEANS OF THE BEAUFORT, N. C, REGION. 377 



Tribe PENEIDEA. 



Natantia having the third pair of legs chelate but not stouter than the two preceding 

 pairs, the pleura of the first abdominal segment not overlapped by those of the second, 

 the abdomen without a sharp bend and the first abdominal appendages of the male with 

 a sexual apparatus. The gills are never developed as phyllobranchise. 



This tribe comprises 2 families, both of which have representatives in the Beaufort 

 fauna. 



Family PENEIDAE. 



Peneidea having the last two pairs of legs well developed and the gills numerous. 

 This family comprises 23 genera, of which 4 are represented in the Beaufort region. 



KEY TO THE GENERA OF THE BEAUFORT REGION. 



a. Integument thin; abdomen smcxjth, not carinate anteriorly; trunk legs with exopodites; pleopods 



biramous (Subfamily PeneiruB). 



b. Endopodite of first maxilla elongate and segmented Peneus. 



66. Endopodite of first maxilla short and unsegmented. 

 c. Exopodites present on all, or all but the last pair of legs; antennular flagella moderately long; 



no pleurobranchiae on the last two thoracic somites Trachy peneus. 



cc. Exopodites wanting on all the legs; antennular flagella short; no pleurobranch on the last thoracic 



somite Parapenceus. 



aa. Integument rigid; abdomen more or less carinate throughout its length and marked with fturows; 

 trunk legs without exopodites; pleopods all uniramous (Subfamily Sicyonina:) Sicyonia. 



Genus PENEUS Weber. 



Peneus Weber, 1795, p. 94. 



PentEus Fabricius and most subsequent writers. 



KEY TO THE SPECIES OF THE BEAUFORT REGION. 



a. Dorsal stuiace of carapace with a carina extending from the rostrum nearly to the posterior margin 



and bordered on each side by a deep sulcus brasiliensis. 



aa. Dorsal carina about two-thirds as long as carapace and with shorter lateral sulci seliferus. 



Peneus brasiliensis Latreille. Shrimp. PI. xxv, fig. 6. 



Penceus brasiliensis Ivatreille, 1817, p. 156; Stimpson, 1S71, p. i32;Coues, 1871, p. 124; Kingsley, 1878-79, p. 330: Rathbun, 

 1901, p. 100; Sumner, rgii, p. 665. 



Integument thin, polished, and translucent. Carapace with a high median carina, continuous in 

 front with the rostrum; extending back almost to the posterior margin of the carapace, and bordered 

 on each side by a deep and broad sulcus; posterior half of carina with a median longitudinal groove; 

 anterior half arcuate, highest above orbit and with nine or ten sharp serrations, the posterior one of 

 which is almost halfway back on the carapace and remote from the others while the anterior six or seven 

 are on the rostrum proper. Lower margin of rostrum with two or three spines, the tip slender, hori- 

 zontal, and imarmed. Anterior margin of carapace with a strong spine below the base of the eyestalk 

 from which a carina extends backward nearly to the well-marked hepatic spine. Cervical groove 

 extending only hallf way from hepatic spine to dorsal carina. A subhorizontal suture below the hepatic 

 spine. 



Fourth, fifth, and sixth segments of the abdomen carinate, the sixth having the carina bordered 

 on each side by a sulcus. Telson with a deep median groove and an acuminate tip. Eyes large and 

 prominent , on rather slender stalks. Peduncle of first antenna slightly exceeding tip of rostrum . Second 

 anteima with its scale longer than rostrum, flagellum about one and one-half times as long as body. 

 Legs slender and rather short, the three anterior pairs chelate. Pleopods well developed, all except 

 the first pair provided with two foliaceous branches. 



Length of a female, tip of rostrum to tip of telson, 158 mm. ; carapace, 52 mm. 



