S. H. SCUDDER ON PALAEOZOIC COCKROACHES. 29 



is with little doubt a comparatively late development, and we may not look upon the 

 tegmina as a contracted form of the wings; but rather, at the disappearance of the externo- 

 median vein in the tegmina as one stage in the increasing heterogeneity of the organs of 

 flight, as we pass from ancient times to the present; indeed the hind wings of insects in 

 general contain far more indications of the earlier structure and ornamentation of the 

 wings than the front pair. 1 As one example of this we And that the externomedian vein 

 was perfectly developed in the front wings of all the palaeozoic cockroaches, and although 

 probably some of the different nervures were sometimes blended at the base (e.g., Etoblatt. 

 russoma, Petrabl. gracilis), apically each vein was always developed quite separate from 

 the others. 



This is a distinction of prime importance, and so far as we can discover, there is not a 

 single exception in ancient or modern types. In all the palaeozoic species, the externo- 

 median exists as an independent vein; in all modern species the vein itself is blended witli 

 the scapular, and can only be occasionally recognized near the extremity by its branches. 



Besides this difference there is another which, although of less importance, is perhaps as 

 constant and certainly is significant. In palaeozoic cockroacbes the anal veins of the fore 

 wing, as first noted by Goldenberg, impinge upon the border, just as the}' do in the few 

 hind wings which are preserved. In living cockroaches, the branches of the anal vein in 

 the hind wing, preserving here again the ancient characteristics, impinge upon the margin 

 of the wing; while the specialization of the anal area of the fore wing — a distinctively 

 Blattarian feature — has gone so far as to affect the direction of the veins, which do not 

 impinge upon the border, but run parallel to it and strike the anal furrow. 



For these reasons, as being of fundamental importance in the structure of the tegmina. 

 and indicative of the profound changes the entire group of cockroacbes has undergone since 

 its origination, it appears necessary to separate the palaeozoic cockroaches from those 

 existing at the present day as a distinct subfamily type. 



In reviewing the existing species, in order to obtain some clue among them to the 

 nearest allies of the palaeozoic cockroaches, it would appear that very little resemblance 

 exists between the fore wings of the ancient species and those of the Blattariae spinosae, 

 as compared with those of the Blattariae muticae. Further than this it would perhaps 

 hardly be possible to go, unless indeed we were to compare some of the Blaberidae of the 

 present day, comprising the giants of the time, with some of the ancient types, which. 

 while generally larger than recent forms, also often boast of their very great size. Unfor- 

 tunately w r e know almost nothing of the structure of the legs in the ancient cockroaches; 

 they have been preserved, so far as appears, in only one or two instances. In one, Blat- 

 tina Tischbeini, Goldenberg speaks of a fragment of a hind leg, consisting of the femur 

 and tibia with traces of spines (Spuren von Dorneii); but as neither his illustration nor his 

 description show whether the spines occur on the femora or on the tibiae, we have no proof 

 as to whether the former should be considered spinosae or muticae. In the illustration of 

 the other (Anthracobl. sopita) no spines appear; ami the describer of this species, Dr. 

 E. Geinitz, gives no further account of the legs than their size ; perhaps their preservation 

 allows of no further statement, but this point should be studied. 



1 This point, which I hope to expand and illustrate on reflect how commonly the hind wings of insects are < :on- 

 ai miller occasion, is what might well he expected when we cealed by the front pair, when the insect is ;it rest. 



