Boone, Crustacea, Cruise of "Alva," 1931 141 



into a conspicuous right-angled tooth, inside of which the upper 

 surface of the lower finger is deeply excavate for the reception 

 of the oblique, long tooth of the upper finger ; beyond this cavity 

 the upper surface of the lower finger is highly channelled medi- 

 ally, the lateral margins are convergent to an acuminate tip, this 

 distal portion extending substantially beyond the tip of the other 

 finger. The latter is short, laterally compressed, very convex dor- 

 sally with the proximal portion narrowed, the distal portion a 

 broad, thickened blunted blade, from the proximal inner angle of 

 which there arises a rounded node-like tooth, directed obliquely 

 backward. The inner lateral cutting edge of the lower finger is 

 trisinuate. 



The second pair of legs are very thin, subequal, when extended, 

 reaching almost to the base of the fixed finger of the great cheliped. 

 The ischium is 3 mm. long; the merus is 3 mm. long; the carpus 

 is 3.2 mm. long; the first joint is 1.5 mm. long, the second joint is 

 0.5 mm. long, the third joint is 0.45 mm. long, and the fourth 

 joint is 0.75 mm. long ; the propodus has a total length of 1.5 mm., 

 the palm being one-half of this. 



#'■#'*# '** f' -f' v" ^ -> •* * i- • ■' 



Text figure 11 — Alpheus explorator Boone, type: distal joints of third leg, 



showing the articulated spines on the inferior lateral margin 



of the propodus, greatily enlarged. 



The first, second and third pairs of ambulatory legs are simi- 

 lar, successively slightly shorter, all exceedingly slender; the 

 ischium of the first pair is 1 mm. long or two-fifths as long as 

 merus, which is 2.5 mm. ; the carpus is 1.5 mm. long; the propodus 

 is 3 mm. long, distally cuffed on upper margin with bristles, spread 

 fan-like; the dactyl is 1.6 mm. long, curved, dorsoventrally lami- 

 nate, with the lateral margins tapered to an acuminate tip. 



