6 



rUOCEEDINGS OF THE NATIOiSrAL MUSEUM 



VOL. 75 



Pirst to eighth abdominal segments: In most genera (figs. 4, 10) 

 dorsally divided by one transverse sulcus into a prescutal and a com- 

 bined scuto-scutellar area, more rarely, in Agelastica alni (fig. 15) 

 and Sermylassa h^aJensis (fig. 14), divided by two transverse sulci into 

 a prescutal, a distinct scutal, and a distinct scutellar area. The 

 prescutal area and the scuto-scutellar area (in Agelastica and Sermy- 

 lassa, the scutellar area) each carrying on both sides an interior {int) 

 and an exterior {ext) sclerite. The scutal area, when distinct, carrying 

 either a small {Agelastica) or a well-developed sclerite {Sermylassa). 

 The interior prescutal sclerite and the interior scuto-scutellar sclerite 

 usually fused in the sagittal line with the corresponding sclerites of 

 the opposite side; the exterior scuto-scutellar sclerite nearer the sagit- 

 tal line than the exterior prescutal sclerite. The parascutal area 

 {pasc) marked above by a few longitudinally placed impressions of 

 muscles corresponding to the noto-coxal muscles of thorax (f) and 



Fig. 3. — Diagram of Typical Abdominal Segments. Foe 

 Letteking see Text" 



below limited by the dorso-lateral sulcus (6?Z) ; the area never extend- 

 ing down to the ventro-lateral sulcus as in thorax. The parascutal 

 area normally carrying two sclerites, one anterior to the spiracle, the 

 anterior parascutal sclerite {ant), and one posterior to the spiracle, 

 the posterior parascutal sclerite {post). Spiracle in most of the 

 larvae placed directly in the soft skin^ but sometimes lodged in a 

 special sclerite, the spiracular sclerite (figs. 4, 11, 14), and sometimes 

 located in the anterior parascutal sclerite (fig. 18). The anterior and 

 the posterior jDarascutal sclerites fused in a few larvae (fig. 3), the 

 anterior sclerite absent in many larvae (figs. 7, 24) and excep- 

 tionally (figs. 1, 9) the anterior and posterior sclerites both undevel- 

 oped. The epipleural area {epi) subrectangular, carrying one well- 

 developed sclerite. The hypopleural area (fig. 7) situated directly 

 below the ventro-lateral sulcus, carrying one well-developed sclerite. 

 The sternal region (fig. 5) with an unpaired eusternal area and a 

 paired area probably formed by fusion of the parasternal and ster- 

 nellar areas; the presternal area absent; the poststernellar area absent 

 in some genera (fig. 6), present in others (fig. 5), and in some of the 

 latter genera (fig. 15, Agelastica) developed as an intersegmental 



