178 STALK-EYED CRUSTACEA. 



The second pair of legs are a little longer than the first pair, with a 

 longer and slenderer chela. The second segment (basipodite) is armed with 

 a small spine at the distal end of the inferior edge. The inferior edge of the 

 merus is armed with thirteen spines. The carpus is armed with one long 

 spine at the distal end of its lower margin. The chela is unarmed, except- 

 ing the pectinate grasping edges of the fingers. 



The third pair of legs reaches forward a little beyond the proximal end 

 of the chela of the preceding pair. The coxa and basis are robust, the suc- 

 ceeding segments tapering to a thread-like tenuity in the propodite and dac- 

 tylus. All of the segments are naked and xmarmed. The merus contributes 

 one half to the length of the whole appendage, being more than twice as 

 long as the propodite. The dactylus is shorter than the carpus. 



The fourth pair of legs are very short, reaching only to the proximal end 

 of the merus of the second pair of legs. The inferior margin of the dactylus, 

 propodite, and distal end of the carpus is beset with coarse bristles. 



The fifth pair of legs, when extended, attain to the middle of the merus 

 of the second pair. The dactylus is flattened, broad, rounded at the distal 

 end, and furnished with long marginal setoe. 



Length, 145 mm.; carapace, including the anterior dorsal tooth, 55 mm. 



Station 3384. 458 fathoms. 1 specimen. 



This species is second only to P. princeps Smith, in size. It is most 

 nearly related to P. tarda Kroyer,* from the North Atlantic. It differs from 

 the latter in having the dorsal line of the carapace more convex, the pos- 

 terior part of the carapace higher in proportion to the anterior part, the 

 dorsal keel of the carapace rounded except on the anterior gastric region, 

 and the anterior roairum-like tooth longer and differently shaped. The 

 proportional length of the segments of the third pair of legs appears to be 

 quite different in the two species : in P. tarda, according to Kroyer, the pro- 

 podite and dactylus are of equal length and four times as long as the carpus, 

 while in P. magna the dactylus is even shorter than the carpus, which is 

 itself only one sixth as long as the propodite. In P. tarda, according to 

 Kroyer, the lower margin of the second segment of the second pair of 

 legs is furnished with three spines ; in P. magna this margin is miarmed 

 but for the tooth at its distal end. 



• Naturbist. Tidsskr., 2 H., I. 453, 1845; Voyages dc la "Recherche" tu Scaudiuavie, etc., Crustacfo, 

 Plate VI. Fig. 1. 



