xxxiii, '22] ENTOMOLOGICAL NEWS 299 



The Tracheation of the Wings of Early Larval Instars 



of Odonata Anisoptera, with Special Reference 



to the Development of the Radius. 



By RUDOLF G. SCIIMIEDER, M.A., University of Pennsylvania, 



Philadelphia. 



(Continued from page 262) 



In the wings of Gomphns, stages of tracheal development 

 were found which corresponded to those found in Anax. The 

 observations and remarks made concerning the wings of Ana.v, 

 as regards their size at the various stages of tracheal develop- 

 ment, the variability in the number of tracheae and tracheal 

 branches, and the condition of the tracheae, whether simple or 

 fascicled, apply also in a large measure to the wings of Gom- 

 phus, as is shown in figs. 9-14. (Figs. 9-13 are of G. villosipes, 

 fig. 14 is of G. c.v His.) 



In addition it should be noted that, especially in the earliest 

 stages, the wings of Goniphits show even greater variations 

 than have been described for \-hin.\-. Fig. 9 is a wing 0.12 mm. 

 in length from a larva 8 mm. long. It has only five tracheae, 

 the anal being entirely absent. The radius is branched from 

 its point of origin, the posterior branch is bent at right angles 

 and its distal portion passes caudad and crosses over the four 

 anterior branches of the media. It is often found that in early 

 stages tracheae may be very elongated so that their distal por- 

 tions pass either cephalad or caudad along the edge of the 

 wing, and this fact, together with the observation that the 

 courses of the tracheae are at this time indefinite and largely 

 a matter of chance, indicates that, the condition of the posterior 

 branch of R in this wing has no relation to the crossing of a 

 radial branch over J/l and .1/2. which is found in later instars. 



In fig. 10, a wing 0.15 mm. long from a 7 mni. larva, condi- 

 tions are very different from the preceding, there being no less 

 than eleven distinct tracheae originating from the transverse 

 basal trunk. In this wing R is unbranched, and M has but t\\o 

 branches. 



Figs. 11 and 12 are of the front and hind wings respectively 

 of a 10 mm. larva. These wings are 0.23 mm. in length and 

 again show noteworthy variations. 



