169 



EXPLANATION OF THE PLATES. 

 Plate I. 



The drawing;- were made with a camera lueida, using a Bausoh and Loinb ^,; oli.iective 

 witli the lower lens removed and a 2-inch eyepiece. 



Fig. 1. Argix ai>icalis (Say). Blufftou, Iiid., Aiigust 18, 1900, E. B. Wil- 

 liaiusou. Dor.sal view of head, protliorax, aud niesotliorax of rf, disjointed. 



.1 — Head, r/i, compound eye. 



B — Protliorax. PL, posterior lobe. AG, anterior groove. 



C — Mesothorax, tlie metathorax showing underneath. AM, anterior 

 end of mesepisternuni. .Ufx ', middorsal carina. MES, mesepisternum. 

 MI, mesinfraepi.«ternum. //Il', liindwing. F]]', forewing. 



Fig. 2. Argia apicalh (Say). Bluft'ton, Ind., August 18, 1900, E. B. Wil- 

 liamson. Lateral view of prothorax, and mesothorax. 



-IN— Articulating surface for liead. Other lettering as for Fig. 1. 



Plate H. 



The drawings were made with a camera lueida, using a 15ausch and Lomb % objective 

 and 2-ineh eyepiece. 



1. Avgia tibialis (Ramhur). Bluifton, Ind., June 17, 1901, E B. Will- 

 iamson. Anterior end of mesepisternum of -J. 



2. Aiyi,! tihiali.^ (Ramlmr). Blutfton, Ind., June IT, 1901, E. B. Will- 

 iamson. Anterior end of mesepisternum of ^ . 



B. Argia sednix (Hagen). Fort Wayne, Ind., July 18, 1901, E. B. W^ill- 

 ianison. Anterior end of mesepisternum of (^. 



4. Argi(( xnbila (Hagen). Fort Wayne, Ind., July 18, 1901, E. B. Will- 

 iamson . Anterior end of mesepisternuni of V • 



5. Argia riolacca (Hagen). Tippecanoe River, Ind., July 2, 1901, E. B. 

 Williamson. Anterior end of mesepisternum of rj'. 



6. Argia riolacca (Hagen). Pittsburg, Pa., June 15, 1899, E. B. W^ill- 

 iamson. Anterior end of mesepisternum of 9 , 



7. Argia apicalis (Say). Bluffton, Ind., June 2, 1901, E. B. William- 

 son. Anterior end of mesepisternum of (^. 



8. Argia apicalis (Say). Blutfton, Lid., June 2, 1901, E. B. William- 

 son. Anterior end of mesepisternum of $. 



9. Argia pufrida (Hagen). Bluffton, Ind., June 17, 1901, E. B. Will- 

 iamson. Anterior end of mesepisternum of (J . 



10. Argia putrida (Hagen). Fort Wayne, Ind., July 18, 1901, E. B. 

 Williamson. Anterior end of mesepisternum of 9 • 



