434 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxiii. 



species was really the male of Nesippus angustatus; 3, that his Noga- 

 gus angustatus was not the same as Gerstaecker's iV. angustulus; 4, 

 that it was not a Nogaus at all, nor did it even include the male sex, 

 but was made up of two females, an adult with egg strings which he 

 recognized as a female, and an immature female without egg strings, 

 which he called a male. Both sexes of this new Nesippus species 

 have been included in the key on page 425. 



NESIPPUS CURTICAUDIS Dana. 



Plate XXXVI. 



Specilligus curticaudis Dana, 1852, p. 1375, pi. xcv, figs. 6 a-h. — Olaus, 1875, 



p. 352, pi. XXIV, fig. 32.— Thomson, 1889, p. 365. 

 Nogagus curticaudis Steenstrup and Lutken, 1861, pp. 383 and 390. 



Male. — Carapace elliptical, a trifle wider than long, excluding the 

 posterior lobes, with an evenly rounded anterior margin and a slightly 

 concave posterior margin between the lobes. 



Frontal plates narrow-linear and following closely the contour of 

 the frontal margin of the carapace, not appreciably enlarged at the 

 ends as in horealis. Posterior lobes very narrow, reaching nearly to 

 the posterior margin of the third thorax segment, and turned out- 

 ward a little. Eyes visible with difficulty, on the median line in the 

 usual position; just in front of them and separated a little are the 

 large prominent conspicilla noted by Dana (see below), one on eithei 

 side of the body axis. 



The three free thorax segments are about the same length, but 

 decrease regularly in width, the fourth being five-eighths as wide as 

 the second. The lateral lobes of the second segment are narrow and 

 extend diagonally backward as far as. the posterior border of the third 

 segment. 



Genital segment the same width as the fourth segment, elliptical, 

 a little wider than long, and squarely truncated both anteriorly and 

 posteriorly. Its sides are evenly rounded and each shows just in 

 front of the posterior corner a small papilla armed with a single 

 spine. There is a well-defined furrow on either side of the dorsal 

 surface, about one-fourth the width from the lateral margin. The 

 surface between these grooves in the center of the segment is more 

 strongly arched than that of the margins. The abdomen is trian- 

 gular, considerably wider than long, with the apex projecting between 

 the anal laminae and deeply incised. Anal laminae also triangular, 

 reaching a little beyond the tip of the abdomen, and each armed 

 with three large setse. First antennas rather slender, but both joints 

 armed with long and bushy plumose setse; second pair stout, the 

 basal joint armed with a large roughened knob on its posterior mar- 

 gin, the terminal claw rather short, but stout and strongly curved. 

 Mouth-tube long and slender, with the mandibles protruding at the 



