NATURAL SCIENCES OP PHILADELPHIA. 365 



a little fuscous towards their tips ; $ with the last ventral segment invisible ; 

 9 with the antepenultimate ventral segment truncate, sometimes longitudinally 

 striate in the middle, sometimes rounded and dehiscent. Wings 9 hyaline, hind 

 wings sometimes with violaceous reflections ; veins (J 1 9 brown, except the costal 

 and subcostal veins and their cross-veins which are yellowish-hyaline in both 

 wings ; two or three apical costal cross-veins. In one specimen the subcostal 

 accessory vein throws off but one branch on the right wing, thereby approxi- 

 mating to subgenus C. In $ all 4 wings are subfumose. 



Length to tips of wings 10 13 mill. Expanse of wings 19 25 mill. Length 

 of abdomeu 3 4 mill. Eleven specimens. May be easily confounded with 

 Chloroperla bilineata, Say (noticed below,) but is always distinguishable at once 

 by the sidfs of the prothorax being fuscous or obscure, never yellow. It differs 

 from P. placida, by the prothoracic vitta and by the costal neuration being 

 almost hyaline, so that the cross-veins are seen with difficulty; from P. occipitalis 

 by the vitta, and also by having three ocelli ; and from P. dilaticollis by having 

 three ocelli, and by the accessory subcostal vein not being incurved. The 8th 

 ventral segment ^ is large, the 9th being concealed by it. 

 no appearance of any suture. 



\\ Perla, subgenus B. Accessory vein two-branched ; two ocelli. 



Perla occiptalis ? Pict. > Luteo-fuscous. Head wider than the prothorax, 

 bright testaceous, clouded before with fuscous and with a round black spot on 

 the ocelli; the epistoma is scarcely excavated, and the usual divaricate carina 

 is subobsolete ; the two usual interocular tubercles are prominent and round; 

 antennas fuscous, except the tip of the first joint and joints 2 to about 7, which 

 are luteous ; palpi fuscous. Prothorax one-third wider than it is long, the 

 sides very slightly sinuate, contracted behind, rugulose, the margins fuscous. 

 Pro- and meso-st.ernum luteous. Legs luteous ; femora and tibiae above and 

 also the tarsi fuscous. Abdominal setae clay-yellow, dusky at tip; 9 antepe- 

 nultimate ventral segment truncate. Wings subhyaline, sometimes with green 

 and violaceous reflections on all of them; veins brown, the costa and subcostal 

 apical cross-veins yellowish-brown; accessory vein not incurved at its origin. 

 The (5\ which is hitherto unknown, differs from 9 in being entirely luteous 

 beneath, and in the four wings being fumose. Abdomen and venter constructed 

 as in $ P. fiavescens. 



Alar expanse 23 29 mill. Length of abdomen 3 3 mill. Differs from P. 

 dilaticollis by the subcostal vein being direct, and from P. occipitalis by the 

 veins being brown, not testaceous. One rj\ four 9- 



g Perla. Subgenus C. (New.) Accessory subcostal vein throwing out only 

 one branch; abdomen very long ; two ocelli ; several subcostal apical cross- 

 veins and several postcostal* cross-veins in the anterior wing. 



The (?, which is hitherto unknown, differs from 9 in being entirely luteous 

 beneath, and in the four wings being fumose. Abdomen and venter con- 

 structed as in (^ P. fiavescens. 



Perla producta, n. sp. Brown. Head wider than the prothorax, with the 

 U3ual divaricate carina prolonged nearly to the tip, and obscurely reverting; 

 clay-yellow or obscure luteous, clouded with fuscous at tip, with a black or 



* I apply this term to the posterior basal corner of the wing, or poslcostal space 

 (espace poatcostal,) in which sense it is used throughout the Synopsis, and in Monographie 

 des Calopterygines ; (see Plate I., fig 1). Mr. Uhler, probably through some clerical or 

 typographical error, is made to say, in the Glossary affixed to the Synopsis, that " Post- 

 costal " is synonymous with " Postcubital." That this cannot possibly be so, at least 

 in Dr. Hagen's nomenclature, may be easily seen by any one who possesses a copy of 

 the Synopsis. The genus Agrion, as distinguished from the genera Pscudostigma and Me- 

 cistogaster, which have one or two series of areoles in their postcostal space, is there 

 characterized by having the postcoital space simple," (p. 74); and on inspecting the 

 diagnoses of the 47 N. A. species of Agrion, it will be found that they have a number of 

 postcubital croBS-veins ranging from 7 to 16. 



1862.] 



