MUSEUM OF COMPARATIVE ZOOLOGY. 27 



are stiff and more calcareous than the rest of the appendage. The outer and 

 anterior of these lobes (d) is the larger, and is alone exposed as seen from below 

 in the natural position of the appendages, while the inner (e) is somewhat 

 triangular, with a narrow base of attachment, and is curved round above the 

 other lobe, and serves to prolong the dorsal wall of the efferent passage, or, 

 perhaps, as a valve for closing its orifice. 



The second maxillipeds (fig. 6) are apparently wholly without exopodal 

 or epipodal branches, and are so short that they reach but little beyond the 

 ischia of the third pair. The ischium and merus are very short, together little 

 more than half as long as the carpus, and both are setigerous along the inner 

 edge, while the ischium has in addition a series of dentiform tubercles. The 

 carpus is about two thirds of the whole length, nearly twice as long as broad, 

 compressed vertically, and much broader in the middle than at either end, and 

 setigerous, but not dentate or tuberculous along the inner edge. The propodus 

 is less than half as long and less than half as wide as the carpus, while the 

 dactylus is still smaller, tapered distally, and terminated in a slender curved 

 and spiniform tip, and both propodus and dactylus are thickly armed with setae 

 and small spines. 



The external maxillipeds (fig. 7) are long and slender, reach, when extended, 

 nearly to the bases of the peduncles of the antennula3, and are well clothed 

 with hairs and setse, but unarmed either with teeth or spines. There is a very 

 small and rudimentary appendage («), apparently representing the epipod, 

 upon the outer side of the protopod. The ischium is a little longer than the 

 merus and carpus combined, and a very little stouter than the merus. The 

 merus is about two thirds as long as the ischium, while the three distal 

 ments are subecpial in length and together a little longer than the merus, the 

 carpus and propodus tapering slightly distally, while the dactylus is slightly 

 curved and tapers regularly to an acute tip. 



The great chelipeds are smooth and naked throughout, except the prehensile 

 edges of the digits of the chelae, and differ somewhat in size in different indi- 

 viduals, varying in length from about two and a half to nearly three times the 

 length of the carapax, but the differences are apparently entirely independent of 

 sex. The coxa is very stout and broad, far stouter than any of the succeeding 

 segments, and much broader than the coxa? of the other legs. The basis is 

 completely anchylosed with the ischium, which is expanded distally bat at the 

 same time strongly compressed vertically, strongly curved upward so as to fit 

 the side of the carapax when turned out at right angles to it, and reaches, in 

 this position, a little above the edge of the carapax, or, when turned forward, 

 to the base or beyond the middle of the antenna! scales. The merus is two 

 thirds to four fifths as long as the carapax, compressed like the merus. but con- 

 siderably expanded proximally, contracted in the middle and distally to mar 

 the tip where it is again expanded and thickened at the articulation with the 

 carpus ; the posterior edge is armed with an acute spine at the distal extremity, 

 and with either one or two similar ones on the proximal half, while the an- 

 terior edge, except near the base, is armed with a scattered series of minute 



