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PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 41. 



the terminal one very minute. Tiie mandible has both the molar and 

 the incisor processes unusually short and stout. The maxUlula and 

 maxUla are of normal form; the palp of the former carries two setae. 



The third maxillipeds have the basis expanded distally, where its 

 width is nearly one-fourth of its length along the inner edge; its 

 inner distal angle is produced into a strong, acute tooth; the ischium 

 is very wide and is produced externally into a stout tooth; the merus 

 is not more than one- third of the width of the ischium; the terminal 

 segments are very slender and in the specimens dissected they are 

 doubled back behind (i. e., on the inner or upper surface of) the basis. 



The first legs are unusually short, hardly extending beyond the 

 antero-lateral angle of the carapace; the distal segments together 



85 86 87 



Figs. 85-87.— Diastylopsis dawsoni, immature female. 85, Third maxilliped; 86, first leg; 87, 



second leg. 



are about two-thirds as long as the basis; the last three segments 

 successively diminish in length. 



The second legs have the carpus nearly twice as long as the two 

 distal segments together. 



The third and fourth pairs of legs have each a very minute vestige 

 of an exopod, apparently unsegmented. 



The peduncle of the uropods extends for nearly half its length 

 beyond the telson. It has a closely set series of slender spines along 

 its inner edge; the exopod is more, and the endopod less, than half 

 the length of the peduncle; of the three segments of the endopod the 

 first occupies about half of its length and the third is much longer 

 than the second; the marginal spines of both rami are slender. 



Male. — Total length, about 9 mm. 



In general form the carapace resembles that of the female and it 

 is similarly marked with four transverse lines; there is, however, no 

 antennal notch, the antero-lateral margin sloping backwards from 

 the lower edge of the pseudorostrum with hardly an indication of 



