372 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xxxiii. 



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terior lobes; lateral areas of medium width, the transverse grooves 

 crossing them nearly at the center; posterior lobes long and narrow, 

 their tips extending under the third dorsal plates for some distance; 

 posterior margin concave. Frontal plates not well defined nor promi- 

 nent; eyes small and situated about two-fifths of the distance fi-om 

 the frontal margin. 



The fused second and third thorax segments rather short; first 

 dorsal plates large and extending out beneath the posterior lobes 

 nearly to the lateral margins of the carapace. These plates are semi- 

 circular and end in blunt spines at their anterior corners. Second 

 dorsal plates rudimentary and narrow, leaving a space on either side 

 between their lateral margin and the posterior lobe of the carapace. 

 Third dorsal plates enormous, covering the entire genital segment 

 except the very tips of the posterior lobes; each plate is one-half 

 longer than the carapace on the mid-line, and together they are con- 

 siderably wider than either the carapace or the genital segment, pro- 

 jecting far beyond the lateral margins of the latter. Their outer 

 margins are strongly curved, their posterior margins nearly squarely 

 truncated, and there is a wider space between their inner margins 

 than in most species. They are smooth and without any trace of 

 spines. Genital segment broadly elliptical, a little wider than the 

 carapace, but longer than wide, its posterior lobes wide and bluntly 

 rounded, and turned in toward each other but not overlapping. Pos- 

 terior sinus one-third the entire length, much enlarged at the base, 

 and showing plainly there the dorsal surface of the sixth segment 

 lobe. This latter is much longer than in coleoptratus or denticulatus, 

 with parallel sides and an evenly rounded posterior margin, and it 

 extends backward about half the length of the sinus. 



Abdomen relatively as large as in denticulatus, but much wider pos- 

 teriorly, being subquadrangular; anal laminae large and broad, each 

 tipped with a few coarse spines. The base of the abdomen reaches 

 forward to the center of the genital segment and is about one-third 

 the width of the latter, while the ends of the anal laminae just reach 

 the tips of the posterior lobes. 



First antennae slender and small; second pair large and stout, with 

 a long and strongly curved terminal claw; the basal joint carries a 

 stout spine behind the adhesion pad. 



First two pairs of adhesion pads small, those on the base of the 

 second antennae reduced to mere points. Two small circular pads 

 on the basal joint of the first legs; the three pairs on the apron of the 

 third legs arranged as in coleopiratus , two side by side on each half of 

 the leg and one at a little distance, nearer the mid-line. Mouth tube 

 exceptionally long and slender; second maxillae also long and rela- 

 tively larger and wider than in the other species here described. The 

 terminal joints of these maxillge are boot-shaped, and are folded over 



