Color. — Generally yellowish gray; carapace 

 greenish above, with two triangular white spots; 

 blackish above base of legs (various authors). 



Habitat. — The species has been reported from 

 rocky or coarse shell bottoms (Rathbun, 1925) ; 

 a few feet to 20 fathoms. 



Type locality. — West Indies. 



Known range. — Off Beaufort Inlet, N.C. ; 

 through Bahamas to west coast of Florida ; Cape 

 Sao Roque, Rio Grande do Norte, Brazil. 



Remarks. — Garth (1946) gave a detailed com- 

 parison of this species with its Pacific counter- 

 part, T. laniellifrons. 



Subfamily Acanthonychinae 



Eyes without true orbits; eyestalks very short 

 or sometimes obsolescent, either concealed beneath 

 an anteriorly produced supraocular spine, or sunk 

 in sides of a huge beaklike rostrum ; a postocular 

 spine or process sometimes present, but not 

 excavated for reception of retracted eye. Basal 

 antennal article elongate but truncate-triangular. 

 External maxillipeds with merus as broad as 

 ischium. Dactyls of walking legs prehensile or 

 subchelate; last three pairs of legs often dis- 

 proportionately short compared with [first] pair 

 (Alcock, 1895). Postocular spine not cupped (ex- 

 cept in Sphenocarcinus) ; rostrum either simple 

 or two-spined; palp on third maxilliped arising 

 from anterointernal angle of merus (Rathbun, 

 1925). First pleopod medium stout, apex most 

 varying (hammer-shaped; divided into three or 

 four lobes; etc.) ; second pleopod short (Stephen- 

 sen,- 1945). 



KEY TO GENERA OF ACANTHONYCHINAE IN THE 

 CAROLINAS 



a. Rostrum double ; seven free abdominal segments In 

 both sexes Sphenocarcinus (p. 248). 



aa. Rostrum single or secondarily bifurcate ; six free 

 abdominal segments in male, five in female 



Epialtus (p. 249). 



Genus Sphenocarcinus Milne Edwards, 1878 



Garth, 1958, p. 217. 

 Sphenocarcinus corrosus Milne Edwards 



Figures 227, 233C 



Sphenocarcinus corrosus Milne Edwards, 1875, pi. 17, figs. 

 5-5c— Hay and Shore, 1918, p. 460, pi. 39, fig. 1.— iRathbun, 

 1925, p. 187, text-fig. 73, pi. 62 ; pi. 223, figs. 3-5 (rev.). 



Recognition characters. — Carapace subpentago- 

 nal, broad behind, anterolateral margin concave, 



Figure 227. — Sphenocarcinus corrosus Milne Edwards. 

 Male in dorsal view, legs of left side not shown, 2 mm. 

 indicated. 



posterolateral margin convex. Dorsal surface 

 deeply channeled, leaving symmetrical, coarsely 

 punctuate, or eroded elevations in regular pattern 

 as follows: a longitudinally placed, trefoil-shaped 

 gastric, a transversely placed cardiac with two 

 deep posterior indentations, a transversely elon- 

 gate intestinal, paired laterals extending from 

 near lateral angles to near eyes, and paired small 

 postocular and larger supraocular elevations; 

 margins of all elevations sharply defined with sur- 

 face finely eroded. Rostrum usually longer than 

 carapace, formed of two pointed horns contingu- 

 ous to near tips, slightly divergent in old indi- 

 viduals. Eye deeply sunk between two low smooth 

 excrescences. Basal antennal article truncate, an- 

 tennal flagelluni hidden beneath rostrum. Epi- 

 stome long, narrow. 



248 



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