50 



ENTOMOLOGICAL NEWS 



[Feb., '22 



in Text-fig. 3, a, appears to correspond to that which Ris suc- 

 ceeded in obtaining for Libellnla, and is certainly quite as early 

 a stage as that figured by Needham in which Rs is shown not 

 crossing- M at all. The next instar to this is shown in Text-fig. 

 3, b, and this is certainly either earlier than, or as early as. 

 that in which Needham figures Rs as crossing Ml only. Sev- 

 eral larvae of Gomphus in these early stages were dissected, 

 together with one larva of Hagcnins. All agreed in having the 



R _R 



Text-fig. 3. a, Gomphus villosipes Selys, early larvarl instar, tracheation of portion 

 of forewing, greatly magnified, b, the same, next succeeding larval instar, complete tra- 

 cheation of forewing less highly magnified. 



supposed Rs in the position shown in Text-fig. 3. It is only 

 possible to conclude that Needham's figures of these stages 

 were incorrectly drawn, probably through displacement of the 

 very delicate tracheae. 



Thus we may now be sure that no ontogenetic stages of the 

 supposed development of Rs really exist in the early larval 

 instars of Anisoptera. The position of this trachea being the 

 same in all instars from the earliest upwards is easily under- 

 standable on the theory that it is not the original Rs, but an 

 extension of the subnodal trachea, as I have indicated in the 

 argument presented in this paper. 



A further objection which has to be met is this : If this 

 trachea does not represent the original Rs, where is the original 

 Rs? I have already indicated that the solution of this problem 

 depends upon a study of the known fossils of the Orders 

 Palaeodictyoptera and Protodonata. The solution would take 

 us far beyond the confines of this paper, and is left for a future 

 part of these researches. 



I have referred only briefly, in this paper, to the interesting 

 problem of the cubital and anal veins in the Odonata. It is 

 quite clear, from a study of the fossil record, that the present 



