LIBELLULA. 157 



rior margin flavescent, the base hardly rufescent, the apex sub- 

 infuscated ; pterostigma large, bicolored, yellow, exteriorly fuscous; 

 membranule gray. 



Adult Mule. Thorax and abdomen brownish-black, wings hardly 

 flavescent anteriorly. 



Fifteen antecubitals ; eleven postcubitals ; four discoidal areolets. 



Length 48 52 millirn. Alar expanse 84 88 millini. Ptero- 

 stigma 6 millim. 



Hub. Pecos River, "Western Texas (Capt. Pope). 



16. L. quadrupla! 



Libellula quadrupla Say, Jour. Acad. Philad. VIII, 23, 9. Libellula 

 bistigma Uhler ! Proc. Acad. Philad. 1857, 87, 1. Adult male. 



Reddish-yellow ; mouth and front yellowish, vertex fuscous ; 

 thorax anteriorly rufous, the median suknfs yellowish ; sides pale 

 yellow, with an interrupted, oblique, fuscous stripe ; feet black, 

 base of the femora luteous ; abdomen triquetral, luteous, with a 

 broad dorsal stripe, anteriorly absent, brownish-black ; wings hya- 

 line, the anterior margin, especially at the apex, flavescent, the 

 base with a brownish-black streak ; the apex sometimes infuscated ; 

 pterostigma large, broader in the middle, bicolored, yellow, exte- 

 riorly black ; membranule black. 



Adult Male. Thorax and abdomen nigro-fuscous, altogether 

 pruinose, mouth, front, and the vertex black, wings sometimes 

 hyaline anteriorly. 



13 15 antecubitals; 9 11 postcubitals; three discoidal are- 

 olets. 



Length 40 46 millim. Alar expanse 70 76 millim. Ptero- 

 stigma 5 millim. 



Hob. Baltimore (Uhler); Massachusetts; New Jersey; Mary- 

 land. 



May this not be Lib. cyanea Fab. ? (compare South American 

 Neuroptera.) 



17. L. plumbea! 



Libellula plumbea Uliler ! Proc. Acad. Philad. 1857, 87, 2. 



Rufo-fuscous ; mouth and front brassy-black, margined with 

 yellow (J"), or luteo-fuscous (9); vertex fuscous; thorax in front 

 fuscous, pruinose (J 1 ), or rufous, with the median sulcus yellow- 

 ish (9), sides yellowish-white, with an interrupted, oblique, fuscous 



