468 CALIFORNIA ACADEMY OF SCIENCES. 



Characters of the Major Groups.* 



Suborder I. ZYGOPTEKA. Front and hind wings similar in shape or 

 nearly so, nsnally elevated in repose; no membraunle; with an nnmodi- 

 fied quadrilateral. Males with two inferior terminal abdominal apjieu- 

 dages, penis and its vesicle separate. Nymphs with three caudal 

 tracheal-gills. 



Family 1. Agrionid^. Head transversely elongated; eyes separated 

 from each other; lateral lobes of the labium of two joints, middle 

 lobe bifid. Females with genital valves. 



Subfamily 1. Calopierygince. At least five, and usually more 



antecubitals. 

 Subfamily 2. Agrionbue. Two, occasionally three, antecubitals, 

 wings stalked at base, quadrilateral not cross-veined (except in 

 the S. Amer. Anomisma). 

 Suborder II. ANISOPTERA. Wings dissimilar, hind wings usually 

 broader at base; horizontal in repose; usually with a membranule; 

 quadrilateral modified to form a cardinal cell (triangle) and a supra- 

 triaugle. Males with one inferior terminal abdominal appendage, jjenis 

 and its vesicle connected. Nymphs without caudal tracheal-gills. 



Family 2. .S^schnid^. Triangles of front and hind wings of similar 

 shape (except in some GomphiuEe). Antecubitals of first and 

 second series not coincident, except the first and one other (the 

 latter is variable in position) which two are thicker than their 

 fellows. Postcubitals in the entire second series. Lateral lobes of 

 the labium of two joints. Males often with auricles on 2, and the 

 anal margin of the hind wings excavated. 



Subfamily 3. Gomphince. Head transversely elongated, eyes sep- 

 arated. Abdomen without lateral carinte. Females without 

 genital valves (except in the legion Petalura). 

 Subfamily 4. C or duleg aster ina. Head transversely elongated, 

 eyes a little separated or meeting in a single point dorsally. 

 Abdomen without lateral carinas. Females without genital 

 valves. 

 Subfamily 5. ^iHschnince. Head globose, eyes meeting on the top 

 of the head for a space. Abdomen with lateral carina?. Females 

 with genital valves. 



*Those unacquainted with the technical terms applied to these insects 

 will find the necessary information in the present writer's " Introduction 

 to the study of this group of Insects " in The Transactions of the Amer- 

 ican Entomological Society, vol. xx, pp. 153-218. Philadelphia, October, 

 1893. Also published separately, same paging, by the Society. 



