64 



STALK-EYED CRUSTACEA. 



readily distinguished from the latter by the great size of the right cheliped, 

 the irregularly oval outline of the right chela, the great length of the distal 

 segment of the antcnnular peduncle, etc. 



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Pylopagurus aflanis Fax. 



' Plate XII., Fixf.^-^". 



Bull. Mus. Conip. ZooL, XXIV. 169, 1893. 



This species is nearly related to P. iingitlatiis ^ from which it differs in the 

 following respects : the eye-stalks are longer, and narrower at the distal end • 

 the external prolongation of the second segment of the antenna is longer 

 and slenderer ; the upper margin of the carpus of the right cheliped is armed 

 with two or three spines, the largest of which is close to the anterior border; 

 the outer face of the carpus is smooth save where a light tubercular ridoe 

 runs along the middle. In P. nnffuMus t\m face of the carpus is thickly 

 covered with spinulous granules which assxune larger proportions and a uni- 

 serial arrangement on the superior and inferior margins. On extending the 

 comparison to the large chek;. further differences between the two vspecies 

 become apparent. In both species the external face is fl^at, covered with 

 minute spinulous granules, and surrounded by a border of sharp spines; but 

 in P. ajinis the marginal spines are larger and more irregular, and the flat 

 opercular facet is not sharply defined at the proximal end by the regular 

 arrangement of the marginal spines as in P. iingiilatiis ; instead, one finds the 

 marginal series of spines broken down at this point, thus effacing any distinct 

 limit between the opercular face of the chela and the articular surftice which 

 connects the propodite with the carpus. The inner or lower surface of the 



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which it is composed give rise to long seta) which give the appendage a 

 very hairy appearance when contrasted with P. imguMus ; the inferior 

 border of the chela is conspicuously toothed, while in P. unguJxdus it is entire. 

 The ambulatory legs are more hairy in the Pacific species than in P. itngii- 

 lalus, and their carpal joints are not so distinctly dentate on the superior 

 border. The rasps of the fourth pair of legs are multiserial in both species. 

 The telson P. affinis is symmetrical, subcircular in outline, its posterior border 

 convex and entire ; in P. unguMus, the telson has a deep and wide posterior 

 median notch. 



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