Plate I. 



ANATOMICAL DETAILS AND WING VENATION OF SIMULIID^. 



Fig. 1. — I^atei'al view of thorax of Prosimulium pleurale: ih, Pronotnm ; psci, 

 proscutum ; scU, scutum ; sch, scutellum ; 2)'>^2, mesothoracic post- 

 notum ; ns, metanotum ; pns, metathoracic postnotum ; pph, post- 

 phragma ; w, wing ; h, haltere ; spi 2. prothoracic and mesothoracic 

 spiracles; epsi 2 3, prothoracic, mesothoracic, and metathoracic epi- 

 sterna ; epnii 2 s, prothoracic, mesothoracic, and metathoracic epi- 

 mera ; m, membranous area ; psi 2 3, prothoracic, mesothoracic, and 

 metathoracic sutures; wp2 3, pleural wing sutures; ppt, postparap- 

 terum ; S2, divided mesosternum ; cj^ibs, coxte; abs, abdominal basal 

 scale. The pleural tuft occupies the area covered by the letters ppt 

 and i<?ps in figure. 

 2. — Wing of Simuliimi: A, humeral vein; B, costa; C, subcosta ; D, first 

 longitudinal vein; E, upper branch of radius or third longitudinal 

 vein ; F, lower branch of radius ; O, fourth longitudinal vein or 

 medius; H, fold which has been sometimes considered as the cubi- 

 tus ; I, cubitus or fifth longitudinal vein ; in cases where the fold 

 has been reckoned as the cubitus this vein has been named the anal 

 vein. 

 3. — Wing of Prosimulium. (Explanation as in fig. 2.) 

 4. — Wing of Parasimulium. (Explanation as in fig. 2.) (Original.) 



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