316 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.52. 



Ahdomen. — The abdomon is elongate, slender, lanceolate, with tlie 

 first two segments dorsally flattened, margined along their sides, and 

 strongly compressed below, the remainder rounded above, and taper- 

 ing to the apex. If the fused second and tliird tergites be con- 

 sidered as two segments, there are eight dorsal segments in the female 

 and six ventral, while the male has seven segments both dorsally 

 and ventrally. The tergum of the first segment is narrow at its 

 attachment to the propodeum between the hmd coxae, and gi-adually 

 widens to the apex. There is a median basal excavation and the 

 sides are usually widened slightly at the spiracles which are located 

 much nearer to the base than to the apex of the first segment. The 

 tergites of the second and thhd segments are firmly united, the 

 division between them at most taking the form of a very shallow 

 faint transverse groove. The sides of these segments are also con- 

 stricted to form a sharp margin for the tergite to a point slightly 

 beyond the actual termination-of the second segment. On the sides 

 the suture between these two segments shows distinctly. The 

 spiracles of the abdomen except the first are located on the sides of 

 the segments, and all of them are small and round. There is a trans- 

 verse fringe of relatively long upright hairs just before the caudal 

 margin of all of the segments from the third on. The abdomen ter- 

 minates in the ovipositor in the female, this consisting of a pair of 

 closely locked valves forming an elongate, slender, linear tube approach- 

 ing the abdomen in length, which is always pale red in color, pointed 

 at the tip, and normally hidden by a pair of black sheaths, both of 

 which are fully as long and are very slightly swollen at the tips, v/liilc 

 they are strongly concave within and are sparsely clothed externally 

 with rather stout hairs. The copulatory appendages of the male con- 

 sist of tliree rouglily triangular lobes, the median, dorsal one with 

 a sharp median longitudinal ridge below, wliile the other two ventral 

 lobes are flap-like. An examination of these lobes in the males of 

 three widely separated species of the subfamily Agathinae failed to 

 show any differences that appeared to be of value for even specific 

 identification, so no further attempt was made to study the genitalia. 



Pubescence. — ^All of the hairs of the body proper — that is, the head, 

 thorax, and abdomen — seem to be light colored and often whitish. 

 Then- appearance is somewhat deceptive at times, however, as they 

 are often translucent, and appear to take on the color or shade of the 

 background against which they stand. 



MEASUREMENTS. 



With the exception of the sets of measiu*ements given for the 

 head, all of the lengths, as of the body, wings, etc., are given in 

 millimeters. The head measurements were made with a micrometer 

 eyepiece, with a scale 5 mm. in actual length and divided into 50 

 units, inserted in the right tube of a Zeiss binocular microscope. 



