1913.] NATURAL SCIENCES OF PHILADELPHIA. 247 



both Epallagid (Calopterygine) and Agrionine affinities. It had the 

 nodus at only three-tenths of the wing-length.*' 



No Cretaceous Zygoptera are listed by Handlirsch. 



No ontogenetic data showing a proximal shifting in position of the 

 nodus in any Zygopteron seem to have been published. If the 

 evidence that may be drawn from the hypothetical descent of 

 Agrioninae (Selys) from Calopteryginse (Selys) be left out of con- 

 sideration, there yet appears to be good paleontological support, 

 as sketched above, for the statement of Needham^^ that shortening 

 of the subcosta and retraction of the nodus toward the base of the 

 wing is a developmental tendency away from the generalized con- 

 dition of a long subcosta and a nodus remote from the wing-base. 

 Yet it must be pointed that an upper Liassic fossil is known in 

 which the subcosta ends at only .15 of the wing-length. This is 

 Protomyrmeleon hrunonis Geinitz, for which Handlirsch has erected 

 the suborder Archi-Zygoptera and which he even suggests^^ may have 

 been a connecting link between the Protodonata and the Agrionidse 

 ( = Agrioninae Selys) . Should such an ancestry for the latter group 

 ever be demonstrated, the retraction of the nodus in living Odonata 

 could not have the same significance, as a sign of specialization, which 

 Needham has given it. The alternative suggestion of Handlirsch, 

 that Protomyrmeleon is simply an analogue to the Agrionidse (Agri- 

 oninae Selys) whose descendants have become extinct, seems at 

 present the more probable. 



2. The Number of Antenodal Cross-veins. — A priori one might expect 

 retraction of the nodus to be accompanied by a decrease in the 

 number of antenodal cross-veins. No such proportional reduction 

 exists, however. The two Calopterygine genera cited on p. 246 anted 

 as having the most retracted nodus in that whole group, Chalcopteryx 



^ Still another Jurassic (Eichstadt) fossil is the Agrion eichstdttense of Hagen, 

 listed by Handlirsch as Malmagrion eichstdttense {Foss. Ins., p. 599). Hagen 

 says of it {Paleontographica, X, p. 119, 1862): "Die Fliigel sind 21 mm. lang, 

 sehr schmal .... Der. Nodus liegt 6 mm. von der Basis. Das Geader ist 

 nicht deutlich. " His lithographic figure 5, Taf. XIV, agrees with these propor- 

 tions. 



Meunier (Ann. Soc. Ent. France, LXV, pi. 3, 1896) has given a figure labelled 

 "Agrion? eichstattense Hagen type." It is photographic and represents an 

 insect lying in the same position as that of Hagen's figure and of the same 

 natural size. From Meunier's figure the position of the nodus cannot be recog- 

 nized. In his text Meunier says, p. 131, "Agrion eichstdttense Hagen. No. 150. 

 Type de cet auteur. Paleontographica, t. x, p. 118 a 119, pi. XIV; Cassel, 

 1862." I cannot understand his expression a few lines farther in the same 

 paragraph: "Cette echantillon a beaucoup d'analogie avec celui de Hagen." 



61 Genealogic Study, p. 730. 



62 Foss. Ins., p. 472. 



17 



