NO. 13 STAPH YLINIDAE BLACKWELDER 45 



are placed in tiny circular groups, and these are continued out onto 

 the surface of the plate giving it a striated and spotted appearance. 



The second abdominal segment is composed of a small tergite and ' 

 one small paratergite on each side extending around onto the ventral 

 aspect. The spiracles are more or less united to the tergite. 



The tergite of the second segment (fig. 9 A, tt. 2) h about equal in 

 width to the succeeding segments but is shorter than any. The seg- 

 ments from two to eight, in fact, increase regularly in length. The 

 shape is somewhat fusiform, and the anterolateral angle is produced 

 to enclose the spiracle. The surface is longitudinally marked by a 

 strong suture parallel to the anterior margin, and the vestiture con- 

 sists of a small group of long setae at the posterolateral angles and a 

 very few scattered setae along the posterior margin. The surface is 

 very finely transversely strigulose throughout and is rather densely 

 beset with relatively large lageniform pores. 



The second segment has one paratergite (fig. 9 A, ptt.2) on each 

 side of the tergite. They are rather wider than long, tapering toward 

 each end and are curved around onto the dorsal aspect. No vestiture 

 or sutures have been observed, but the surface is sculptured similarly 

 to the tergite. 



The sternum of the second segment is entirely membranous and 

 unrecognizable. 



The anterolateral corners of the second tergite are slightly produced 

 to embrace a small circular sclerite bearing the spiracle of the second 

 segment. This sclerite is the second abdominal peritreme (fig. 3 A, 

 peri). The spiracle is approximately one-fourth as large linearly as 

 the first abdominal spiracle but is slightly larger than the following 

 ones. The spiracle is very similar in structure to the first abdominal 

 one, having the processes covered with minute hairs that form the sieve 

 plates. 



The membrane separating the tergites of the second and the third 

 abdominal segments bears a minute but very definite pattern of more 

 heavily sclerotized or pigmented areas which are arranged on longi- 

 tudinal irregularly anastomosing strips separated by clear membranes 

 (fig. 9H). This type of membrane is found between the tergites of 

 the second to seventh segments and between the sternites of the third 

 to seventh segments. It fades off laterally to normal membrane in 

 the region of the paratergites. 



The tergites of the segments three to seven (fig. 9 A) , are all nearly 

 rectangular and are marked by a sinuous transverse fold or suture 

 {ts) along the anterior margin. Each bears a spiracle near each antero- 

 lateral angle and is bordered on each side by a pair of paratergites. 



