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129 



ing toward tho distal extremity, finely serrated on the inferior surface, 

 and three or four longer spines on the superior surface ; dactylos short, 

 about one-fourth the length of the propodos, curved, and notched on the 

 under surface, posterior to the apex ; on either side of the base is a wing- 

 like plate. The second pair of guathopoda longer than the first pair, 

 and the antero inferior angle not produced to the same extent; in other 

 respects they are similar. The first pair of thoracic feet shorter than 

 the second, and much longer than the gnathopoda; the posterior margin 

 of the carpus and propodus of both pairs minutely spinulose; dactylus 

 minute. The third pair chelately developed ; carpus large, irregularly 

 quadrilateral, almost as broad as long, the inferior surface rounded, and 

 the anteroinferior angle produced as a long tooth; on the middle of the 

 anterior surface is a large crenulated tubercle, from which rise five or 

 six long, straight hairs. In specimens from the .15 to the .20 of an 

 inch long, there are, in the position of the tubercle, two or three sharp, 

 prominent teeth, springing from a slightly-raised base; and the angle 

 of the carpus is less projecting in the same specimens. Propodus bowed ; 

 when flexed on the carpus reaching to the apex of the tooth at the infe- 

 rior angle — in smaller specimens somewhat longer; a low convexity on 

 the inferior surface opposite the crenulated tubercle of the carpus ; the 

 prominence not crenulated; inferior surface bimarginate. Dactylus 

 present, minute. The posterior apex of the coxa of the third pair acute, 

 prominent ; the meros projecting posteriorly and rounded. The two 

 posterior pairs of thoracic feet subequal, shorter than any of the preced- 

 ing pairs. Telson rudimentary. 



Length of the larger specimens, .40; smaller, .15 of an inch. 



Locality: North Pacific Ocean. Latitudes 4<^ and 21° north; longi- 

 tudes 1270 and 1510 west. Collected May 9 and 20, 1873. 



This species is distinguished from P. scdentaria by the broadly-quad- 

 rate form of the carpus of the third pair of thoracic feet, and by having 

 the carpus of the gnathopoda less produced anteriorly. In other re- 

 spects they are similar. The shape of the hand more nearly resembles 

 the hands of P. custos and P. horneensis] but it is distinguished from 

 both of the latter, by the character of the anterior surface of the carpus 

 and of the propodus. In the latter both the carpus .ind propodus are 

 furnished with a crenulated tubercle ; in custos the tubercle is single 

 and tooth like. There is a striking resemblance between the propodus, 

 and the anterior surface of the carpus of the third pair of thoracic feet, 

 of the smaller specimens of pacifica, and the corresponding parts of P. 

 Bull. K M. No. 7—9 



