Boone, Crustacea, Cruises of "Eagle" and " Ara," 1921-28 191 



segment is as long as the third, with the posterior margin straight in 

 the median region, the postlateral angle produced into a triangular 

 process that projects over the sixth segment and with two carinae 

 forming a V, with the apex directed forward, on the dorsal surface 

 and below this a parallel oblique carina. The sixth segment is nearly 

 one-third longer than the fifth, slender, quadrate, a pair of parallel, 

 longitudinal submedian carinae slightly below, which on either side 

 the posterior margin is produced to a projecting triangulate tooth; 

 the telson is slightly longer than the sixth segment, almost as long 

 as the inner blade of the caudal fan, the tip rounded, a longitudinal 

 carina on each side for the proximal two-thirds of the length and 

 armed with five spinules on each, equally spaced. The inner blade of 

 the fan is long, narrow, with a ridge parallel and near the inner 

 margin, the outer margin more convex. The outer blade is much 

 wider and slightly longer than the inner, the distal margin broadly 

 convex, the outer lateral margin ridged, terminating in a subdistal 

 tooth ; a submedian groove curves distally to this tooth. The margins 

 of the caudal fan are ciliated. 



The antennulae have the three basal articles short, stocky, the 

 shorter branch of the flagellum reaching about as far forward as the 

 subdistal tooth on the outer margin of the seaphocerite ; the inner, 

 slenderer branch extends a short distance beyond the seaphocerite. 



The antennae have a stocky peduncular article, a short, cylindrical 

 second article and a longer, cylindrical third article which reaches to 

 midway the seaphocerite and a flagellum about three-fifths as long as 

 the animal's body. The seaphocerite is about three-fifths as long as 

 the carapace, thick; the outer lateral margin ridged and terminating 

 in an acute spine which projects beyond the remainder of the evenly 

 convex, ciliated, distal margin ; there is also an approximately median 

 longitudinal carina. 



The first leg is short, not reaching beyond the seaphocerite, when 

 extended; the merus elongate, somewhat wider distally; the carpus 

 short, nearly as wide as long; the propodus the longest article, sub- 

 cylindrical, dorsoventrally compressed; the inner lateral margin ter- 

 minating subdistally in a spine-like tooth, the distal margin evenly 

 convex; the dactyl is a short, acuminate, curved finger fitting upon 

 the propodal margin. 



Synonymy. — Crangon septemspinosa Sabine, Suppl. to Appendix to 

 Parry's First Voyage for the Discovery of a Northwest Passage, 

 p. 236, pi. 22, figs. 11-13, 1824.— Ross, Appendix to Parry's 



