246 PROCEEDINGS OF THE ACADEMY OF [May, 



the known Odonata, from the Lias, have been segregated by Hand- 

 lirsch as a suborder, distinct from the existing Zygoptera and Anisop- 

 tera, under the name Anisozygoptera.^^ These insects usually 

 possessed a nodus which lay at about mid-length of the wing. Hand- 

 lirsch considers^'* that, of the recent forms, the Gomphidse and 

 Calopterygidse have unquestionably the closest relations to the 

 Anisozygoptera and are probably direct descendants thereof. The 

 Agrioninae of Selys have usually been looked on as descendants of 

 Calopterygid(or -gine)-like forms." The position of the nodus in 

 Calopteryginae and in Agrioninae, respectively, has been stated as 

 follows : 



"The position of the nodus varies in both the Calopteryginae and 

 the Agrioninae, but in general it is farther from the base of the wing 

 in the former than in the latter. Among the first-named it is probably 

 nearest the haae (one-third the wing-length) in Amphipteryx and in 

 Chalcopteryx,^^ among the second group it is farthest from the base 

 (more than one-third the wing-length) in Archilestes. No Calop- 

 teryginae have the nodus as near to the base as one-fifth the wing- 

 length, but many Agrioninae have it in that position."" 



This statement was based on conditions existing in recent forms. 

 Very little is known of fossil Zygoptera of periods earlier than the 

 Eocene"^ when Dysagrion and fragments named Podagrion abortivum 

 by Scudder appear. From the Jurassic, Handlirsch lists^^ Euphceoj)sis 

 multinervis Hagen, in fair preservation, and four possible but inde- 

 ciphera]:)le species of Pseudoeuphcea, all considered to be allied to the 

 living Epallage, Euphcea, etc., i.e., Calopteryginae of Selys. Euphce- 

 opsis multinervis had the nodus at .44 of the wing-length. Another 

 fossil of the same age is Steleopteron deichmulleri placed by Handlirsch 

 in a separate family Steleopteridae, which is considered to possess 



" L.c, p. 463, August, 1906. 



5* L.c, p. 464. 



s5 Calvert, Trans. Amer. Ent. Soc, XX, pp. 211, 212, 1893; Ris, Zool. Jahrb., 

 Abth. Syst. Geog. Biol. Thiere, IX, p. 623, 1896. 



Cf. Needham, Genealogic Study, pp. 742, 748, 750, 1903; Handlirsch, Foss. 

 Ins., p. 472, 1906; Tillvard, Proc. Linn. Soc. N. S. Wales, XXXVI, p. 600, 1912; 

 XXXVII, p. 406, 1913. 



58 In Chalcopteryx the nodus is at .37 (front wing) or .39 (hind wing) of the 

 wing-length. 



57 Calvert, Ent. Mo. Mag., (2), XIII, p. 31, 1902. 



58 Osborn, The Age of Mammals, 1910, p. 42, places the Green River shales in 

 which these genera occur as equivalent to the Upper Ypresian, i.e.. Middle Eocene. 



59 Fossile Insekten, pp. 595 et seq. 



