NO. 13 STAPH YLINIDAE BLACK WELDER 43 



Each of the first eight segments bears a pair of spiracles in the tergum, 

 and each one except the eighth has one or two paratergites on each side 

 between the tergite and the sternite. 



The first segment is more closely united to the thorax than to the 

 abdomen (fig. 3 A, it. i). The sternite of this segment is not present, 

 the tergite (fig. 9 A, tt. i), one paratergite on each side {ptt. i), and 

 the large spiracles {sp. i) composing the tergum. The tergite is wider 

 than any of the other tergites and is expanded laterally to nearly twice 

 the length at the middle. Anteriorly it is closely united to the post- 

 notum of the metathorax and posteriorly is rather widely separated 

 from the tergite of the second segment. The surface is not marked by 

 any sutures and is rather lightly sclerotized. A narrow strip along 

 the lateral margin {y, y) is somewhat elevated and rather densely 

 clothed with setae. This area is wider posteriorly, and the setae are 

 long in front but becoming much longer posteriorly. The punctures 

 are separated by two to four times their own width and are inter- 

 spersed with tiny circular nonsetigerous punctures. The remainder 

 of the surface except near the midline is sparsely set with very small 

 setae in small punctures, with scattered nonsetigerous punctures also. 

 The surface is finely strigulate except at the middle, where the 

 posterior area is very densely and finely, but strongly, muricate. This 

 murication is continued onto the membrane behind the tergite and 

 expands somewhat laterally. On the ental surface of the tergite the 

 strigulae are serrate on the posterior edge over nearly the entire 

 surface. 



The paratergites (fig. 9 A, ptt. /) of the first abdominal segment 

 consist of a single broad plate on each side of the tergite. They are 

 about one-half as long as the lateral margin of the tergite and are 

 nearly quadrate. Anteriorly each is deeply emarginate to receive the 

 end of the spiracle {sp. i). The paratergites are clothed similarly to 

 the lateral parts of the tergite except that the setae are a little shorter 

 and are densest in front. The posterior margin is unclothed but bears 

 the scattered small punctures similarly to the rest. 



The spiracle of the first abdominal segment (fig. 9 A, sp. i, D) is 

 the largest spiracle on the body. It is about twice as long as wide and 

 occupies the anterior half of the lateral margin of the first tergite. 

 It is formed of an oval plate with a large irregularly oval aperture, 

 which is almost completely closed by two series of narrow branching 

 lobes along the sides, which project in one plane over the aperture and, 

 by means of their very dense covering of minute hairlike projections, 

 form a sieve plate over the whole aperture. These microscopic points 



