Boone, Crustacea, Cruises of "Eagle" and "Ara," 1921-28 211 



five, inclusive, fused, forming one segment. The sternal plastron is 

 wide and flat. 



The antennulae are large and armed with spinulose setae on the 

 exposed face of the long, cylindrical peduncular joint. 



The antennae have the basal joint flat, suboval, with each distal 

 angle acuminate, spinose; the median distal margin deeply excavate 

 for the reception of the second joint which is subcylindrical and armed 

 with a sub-basal spine on its lower face; the third joint is short, 

 bulbous ; the flagellum is fine, composed of fifteen or twenty tapering 

 rings. 



The eyestalk is short, cylindrical, with a short, semioval projection 

 on the cornea, which is large, reniform. 



The chelipeds are equal, of moderate size ; the merus is three-sided, 

 spinose along its anterior lateral margin and armed with acute spines 

 at both anterior and posterior distal angles; anterior face of merus 

 very setose ; the carpus is convex and armed with eight to ten spines ; 

 the palm is smooth, suboval, three-fourths as high as long ; the fingers 

 short, deflected, with spoon-shaped tips meeting. 



The ambulatories have the second and third pairs longest, sub- 

 equal ; the first pair next in length, extending three-fourths the length 

 of the propodus of the second leg ; the seventh leg reaches to scarcely 

 midway the propodus of the third leg; the meral joints of the first 

 three legs are each elongated; that of the first leg is not especially 

 widened, but those of the second and third legs are one-third as wide 

 as long ; the meral joint of the fourth leg is also widened but is only 

 half as long as the merus of the third leg; two fiat, hairless, longi- 

 tudinal carinae separated by a setose area on the upper surface of 

 each meral joint; the anterior meral margins are set with a row of 

 long, acute spines which slightly diminish in size towards the proxi- 

 mal end. On the first, second and third legs each a row of secondary 

 spinules parallels the marginal row; this secondary row is absent on 

 the fourth ambulatory; the posterior lateral margin of the meral 

 joints terminate in an acute subdistal tooth. 



Synonymy, — Acanthopus gihhesi Milne Edwards, Ann, Sci, Nat. Ser. 

 3, Zool., vol, 20, pp, 180 and 146, 1853. 



Leiolophus planissimus Miers, Ann. Mag. Nat. Hist., ser. 5, vol. 1, p.. 



153 (part) 1878. 

 Percnon planissimum Rathbun, Pro. U. S. Nat. Mus., vol. 22, p. 281^ 



1900, (part). 



