412 



BULLETIN 54, UNITED STATES NATIONAL MUSEUM. 



posite, and .situated a short distance from the lateral margins. The 

 first pair of antenna? have the basal article short and somewhat dilated; 

 the second article is a little longer than the first and about half as wide; 

 the third article is shorter than the second; the flagellum is composed 

 of six articles. The first antennae extend two-thirds the length of the 

 fifth article of the peduncle of the second antenna. The second pair 

 of antennae have the first article very short; the second and third are 

 subequal and each is but little longer than the first; the fourth arti- 

 cle is twice as long as the third; 

 the fifth article is one and a half 

 times longer than the fourth. 

 The flagellum is composed of 

 about fifty articles and extends, 

 when retracted, to the posterior 

 margin of the fourth thoracic 

 segment. - The maxilliped has a 

 palp of five articles. The palp 

 of the mandibles is wanting. 



The segments of the thorax 

 are subequal, with lateral mar- 

 gins straight and entire. The 

 epimera are not separated off 

 from the segments, but are per- 

 fectly coalesced. 



The abdomen is composed of 

 a single large segment, rounded 

 posteriorly, with a small rounded lobe between the uropoda. The 

 uropoda are very short, being only 1 mm. long, or one-fourth the length 

 of the abdomen, which is 4 mm. long. The peduncle is about as long 

 as broad and shorter than the branches. The inner branch is one and a 

 half times longer than the peduncle; the outer branch is a little shorter 

 than the inner branch. In the female the first pleopoda are attached 

 close together, as shown in fig. 460 c. 



The first pair of legs are subchelate. The propodus is armed with a 

 single large spine on the inferior margin. The dactylus is furnished 

 with a row of small spines along the inferior margin. 



FIG. 461. MANCASELLVS BRACHYURUS. x 4}. 



