24 Psyche [February 



The anatomy of the body in general in the Plecoptera in- 

 dicates that they are among the most important of the living 

 forms which have departed but little from the condition typical, 

 in many respects, of the ancestors of the Orthoptera-like insects, 

 and the higher orders. The venation of the fore wings of recent 

 Plecoptera, however, does not furnish a particularly favorable 

 basis of comparison in attempting to determine the paths of 

 development followed in the evolution of the higher orders of 

 insects, while the veiiation of the Protorthoptera in par- 

 ticular, and in some respects that of the Protoblattids, 

 (Propalaeoptera) Hadentomoids, (Proplatyptera) Megasecoptera 

 etc., as well, apparently furnish certain servicable clews for 

 tracing the origin of some of the developmental (evolutionary) 

 tendencies exhibited in the wing venation of certain of the higher 

 orders of insects. 



Since the Protorthoptera appear to be as important as any 

 of the fossil forms suggestive of the precursors of the higher 

 insects, it is of some interest to establish as closely as possible 

 the types ancestral to the Protorthoptera. Handlirsch appar- 

 ently derives the Protorthoptera directly from the Palaeodic- 

 tyoptera (or from the Synarmogoidea, which he derived from 

 the Palseodictyoptera) ; but a comparison of the wings of 

 such a Protorthopteron as Spaniodera ambulans, or even 

 the Protorthopteron shown in Fig. 30, with the Protoblattid 

 shown in Fig. 32, would indicate that the Protoblattids are in- 

 termediate between the Protorthoptera and the Palseodicty- 

 optera. In the forewings of the lower Protorthoptera and in 

 certain Protoblattids, the anal veins are numerous, and in the 

 hind wings of certain Protorthoptera there occurs an anal fan 

 very suggestive of that found in many Protoblattids. The 

 character of the cubital vein with its numerous oblique branches 

 (cubital bars) and its rather wide extent in the posterior portion 

 of the fore wing, is strikingly similar in both Protorthoptera 

 and Protoblattids, and the nature and extent of the subcostal 

 bars, or veinlets extending from the subcostal vein to the anterior 

 margin of the wing, are much alike in both groups of insects 

 (Protorthoptera and Protoblattids). When the more primitive 



