432 NEW YORK STATE MUSEUM 



Of these three papers the first named is most complete for the period 

 it covers, and it is the only one containing any reference to the literature 

 of the immature stages. 



The four descriptive papers most continuously referred to in the bibli- 

 ographies of images are: 



Hagen, H. A. Synopsis of tbe Neuroptera of North America. Smithsonian 

 inst. Misc. coll. 1861. 



Calvert, P. P. Catalogue of the Odonata of Philadelphia and vicinity. Am 

 ent. soc. Trans. 1893. 20 : 152-272, 2pl. 



Kellicott. Odonata of Ohio (a posthumous paper, completed and edited by 

 James S. Hiae). 0. state acad. sci. Special papers, no. 2. 1889. 



Williamson, E. B. Dragon flies of Indiana. Dep'tgeol. and natural resources 

 of Indiana. 24th an. rep't 1900. p. 233-333, 7 pi. 



The first of these papers is out of print ; the others may be obtained 

 through the organizations under whose auspices they were published. 



The bibliographies given below, being solely designed to aid the user 

 of this paper, are intended to cover the following points. 



1 The original description of the species 



2 The principal descriptions which have introduced synonyms 



3 All available descriptions and figures in American periodicals 



4 The records of the occurrence of the species in this state ; at least 

 Calvert's summary of such records. (In most cases I have not thought 

 it desirable to go back of this: Calvert's paper is cited on p. 430). 



5 All available descriptions and figures of the nymphs of our species. 

 It will be convenient to treat here as famihes the two groups that are 



so recognized in the descriptive works to which our bibliographic refer- 

 ences refer. These may be separated by the following keys. The tech- 

 nical terms used in the keys are explained in figures 8 to 10. 



KEY TO FAMILIES 



Imagos 



a Triangle {see fig. 9) about equally distant from arculus in fore and hind 

 wing ; stigma with a brace vein at it sinner end (except in Cordulegas- 



ter) Aeschnidae p. 434 



aa Triangle in the hind wing much nearer the arculus than in the fore wing ; 

 stigma without brace vein Libellulidae p. 478 



Nymphs 

 a Labium (see fig. 8) flat or nearly so, without raptorial setae (except in 

 Cordulegast er, which has the labium spoon shaped, and the median 

 lobe cleft at the summit of a prominent median angle into two divergent 



teeth) Aes chnidae 



aa Labium mask shaped or spoon shaped, when closed covering the face up to 

 the bases of the antennae, armed with raptorial setae Libellulidae 



