264 



Illinois Natural History Survey Bulletin 



Fol. 23, Art. 1 



portion lighter brown, frons with a pair of 

 cream-colored marks along lateral margin; 

 thoracic sclerites dark brown. Legs with 

 coxae brown, remainder of segments shad- 

 ing to a chestnut brown, the upper and 

 lower edges of the femora black. Lateral 

 fringe present on segments 3-7. 



Case. — Fig. 904. Length 12 mm., almost 

 square in cross section and smooth in out- 

 line, constructed of wood fragments. 



Adults. — Length 9-11 mm. Head, body, 

 antennae and most of legs dark brown to 

 black, tarsi whitish and abdomen with a 

 wide lateral line; wings tawny, frequently 

 almost white, with a series of pale spots 

 giving a somewhat checkered appearance. 

 Male genitalia, fig. 899: cerci ovate and 

 widely separated to base ; claspers curved, 

 the base narrow, the curve narrow and 

 necklike, the apical portion swollen, nar- 

 rowed to a sharp tip; tenth tergite divided 

 down meson into a pair of long apical proc- 

 esses, each bearing one or two long macro- 

 chaetae directed laterad. Female genitalia, 

 fig. 902, consisting of simple plates and a 

 small bursa copulatrix. 



Neotype, male. — Momence, Illinois: 

 May 4, 1937, Ross & Mohr. 



/'QoaB 



900 C 



Figs. 898-900. — Brachycentrus, male geni- 

 talia. A, lateral aspect; B, dorsal aspect; C, 

 tenth tergite, dorsal aspect; D, apex of clasper, 

 ventro-caudal aspect. 



than long; eighth sternite with apical 



lobes wide and large, fig. 902 



numerosus, p. 264 



Lateral aspect of apical tergite long, 

 apical portion oblique and much 

 longer than deep; eighth sternite 

 with apical lobes narrower and 

 smaller, fig. 901 . . . . americanus, p. 266 



Brachycentrus numerosus (Say) 



Phryganea numerosa Say (1823, p. 160). 



Figs. 901-903. — Brachycentrus^ female geni- 

 Larva. — Fig. 896. Length 12 mm. Head talia. A, ventral aspect; 5, "lateral aspect of 

 with ventral portion dark brown, dorsal ninth and tenth tergites. 



902 A 



NUMEROSUS 



LATERALIS 



