PERLIDES. 155 



furrow, broader in front, straight on each side; hind angles rounded ; 

 fore angles sharp : wings dark hrown ; veins black ; external basilar 

 areolet with ten transverse veins ; terminal areolet with two trans- 

 verse veins; submedian areolet with six transverse veins. Length 

 of the body 5 lines ; of the wings 10 lines. 

 a. Venezuela. From Mr. Dyson's collection. 



Sub-group 2. 



Species mediocres. Prothorax fuscus, rugosus, lateribus rectis. 

 Alse omnino hyalinae et limpidae, venis fuscis. 



Species of moderate size : prothorax with straight sides, brown, 

 rugose : wings quite transparent and colourless, with brown veins. 



47. PERLA VITRIPENNIS. 



Perla vitripennis, Burm. Handb. Ent. ii. 880, 10. Pictet, Hist. 

 Nat. Neur. Perl. 224, 28, pi. 20, f. 1, 2. 



Germany. 



48. PERLA BIC'OLOR. 



Perla bicolor, Burm. Handb. Ent. ii. 880, 9. Pictet, Hist. Nat. 

 Neur. Perl. 226, 29, pi. 20, f. 3, 4. 



France, Germany. 



49. PERLA. TERMINALIS. 



Nigra, subtus lutea ; caput thorace vix latins, margine antico late- 

 ribusque luteis ; antennce nigrce ; prothorax subrugulosus, an- 

 tice paullo latius, submarginatus, subsulcatus, lateribus rectis, 

 angulis acutis ; alee hyalines. 



Black, luteous beneath : head very little broader than the tho- 

 rax, luteous on each side and in front : antenna black, testaceous 

 towards the base : prothorax minutely rugulose, a little broader in 

 front, with a slight border and a slight middle furrow ; sides straight ; 

 angles sharp : wings hyaline ; veins blackish brown ; external basi- 

 lar areolet with seventeen transverse veins ; terminal areolet with 

 four transverse veins ; terminal part of the submavginal areolet with 

 no transverse veins ; submedian areolet with seven transverse veins, 



