334 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.39. 



ERGASILUS CiERULEUS, new species. 



Plate 43. 



Female. — Body more elongate than that of centrarcMdarum, but 

 not as much so as versicolor, nearly three times as long as wide. 

 Carapace elliptical, about as wide posteriorly as anteriorly, with the 

 sides only very slightly reentrant, the longitudinal and transverse 

 diameters being in the proportion of eleven to six. Antennal area 

 two-thirds the width of the carapace and projecting much farther 

 than in any known species, bringing the posterior margins of the 

 second antennae far enough in front of the body of the carapace to 

 leave an open space between the two. Frontal margin evenly 

 rounded; eye removed a little from this margin and covered with an 

 irregular spot of deep blue pigment, so as to be almost invisible 

 (fig. 60). Posterior body (second thorax segment) narrowed abruptly 

 to five-ninths of the width of the carapace. 



Thoracic segments diminishing regularly in width, the third one 

 considerably longer than the second or fourth, which are the same 

 length, the fifth one very short and rudimentary. 



Lateral processes on the dorsal surface of the second segment pro- 

 jecting considerably beyond its posterior margin, narrow and bluntly 

 rounded. Genital segment nearly twice as wide as long, barrel- 

 shaped, with well-rounded sides. 



Egg-strings elliptical, narrower than in centrarcMdarum, but not 

 as narrow as in versicolor, two-thirds as long as the entire body and 

 tapering very little posteriorly. 



Eggs large, arranged in three or four longitudinal rows, about 25 

 or 30 eggs in each string. 



Abdomen, exclusive of the anal laminae, the same length as the 

 genital segment, and abruptly narrowed to half the width of the 

 latter; composed of three segments of about the same length. Anal 

 laminae as long as the last abdomen segment, widely separated, sub- 

 rectangular in outline, and each armed with two setae, the inner of 

 which is twice the length of the outer. 



First antennae apparently seven-jointed, the joints diminishing 

 regularly in width, but of about the same length, except the two 

 basal ones, which together equal one of the others. 



These two basal joints have no setae; the third joint is slightly 

 larger than any of the others, and carries two stout setae at its outer 

 anterior corner; the fourth, fifth, and sixth joints are each armed 

 with a single seta, the terminal joint with a tuft of four or five, none 

 of them very long. 



Second antennae with two stout basal joints, fully twice as wide as 

 long, and two slender terminal joints; first joint with a short powerful 

 muscle along its anterior margin, its posterior margin projecting and 



