28 S. II. SCUDDER ON PALAEOZOIC COCKROACHES. 



deal of study to this family, 1 and having used the tegmina and wings for systematic 

 purposes, have examined an immense series of specimens. These authors distinguish 

 in the tegmina four, in the wings five, principal veins, the distribution of which is 

 pretty constant in their general features, variable in the details; and this permits excellent 

 characters to be drawn for the separation of the genera, etc. The four veins of the tegmina 

 are the mediastinal, the scapular, the internomedian and the anal. 2 The mediastinal vein 

 runs from the root of the wing in a nearly straight course to about the middle of the costal 

 border, throwing off branches to that border. The scapular vein extends to the tip of the 

 wing in a nearly straight course and throws off toward the costal border a number of 

 branches, which maybe simple or forked and disposed with greater or less regularity ; in 

 some instances, especially toward the tip of the wing, it also throws out branches on the 

 opposite side. The anal farrow is an impressed curved line, characteristic of cockroaches, 

 running to the inner margin before the middle of the wing ; within the area thus 

 marked off at the base of the wing are a number of simple or forked anal nervules, often 

 curved, but always straighter than the anal furrow ; these, although they impinge upon the 

 latter, are to be considered branches of the anal vein, for they correspond to the radiate 

 nervules of the longitudinally plicate portion of the hind wings. Between the scapular 

 and anal veins runs the internomedian vein, an irregular nervure, the branches of which 

 may be inferior or superior, longitudinal or oblique, simple or forked, and it is here there- 

 fore that the greatest variation in the manner of distribution occurs, although the relative 

 extent of all the fields may greatly vary. 



The hind wings have two features which are different from what Ave find in the tegmina ; 

 the first is the great expansion of the anal area, the innermost nervule of which is not 

 developed as a furrow ; the second is the presence of a new and distinct vein, the externo- 

 median, lying between the scapular and the internomedian. There is no doubt that in the 

 tegmina this vein should be regarded as amalgamated with the scapular vein, and the 

 blanches occasionally found near the apex of the tegmina, parting from the so-called 

 scapular vein and terminating on the inner or apical margin (e. g., Chorisoneura). as 

 the branches of the externomedian vein ; the more so since in some genera (Ectobia, etc.) 

 the internomedian vein is also amalgamated with the scapular, so that the so-called scapular 

 vein appears to throw branches indifferently to one side or the other of the wing. 



This curtailment or disappearance of the externomedian vein is due according to 

 Saussure to the contraction of the tegmina. In comparing the tegmina with the wings, he 

 remarks : 3 " La portion de l'organe [i. e. the tegmina] situee en arriere de la nervure 

 humerale [scapular vein] s'est tellement contractee que le champ anal a penetre dans le 

 champ disco'idal [internomedian area] et se trouve un peu enveloppe par celui-ci. En y 

 penetrant, il l'a Strangle* a la base, en refoulant la veine diseo'idale [internomedian vein] 

 contre la nervure humerale [scapular vein], en sorte que ces deux nervines se confondent 

 a la base ; et il s'est retreci lui-meme. Dans cette contraction, l'aire vitree [externomedian 

 area] a disparu." We should be careful however not to give Saussure's words a meaning 

 they were not intended to convey; the broadly expanded plicated area of the hind wings 



1 Brunner. Nouveau Systemedes Blattaires. 8°. Vienne, 28. — lb., Miss. Seient. au Mexique, Ins. Orth. 4°. Paris, 



1865, pp. 4-12. — Saussure. Etudes sur l'aile des Orthoptferes 1870, pp. 4-8. 



< Ann. Si-. Nat. [5] Zool., X, pp. 161, seq.; — lb., Orthop- 2 This is Heer's terminology, not Brunner's nor Saussure's. 



teres de l'Amerique moyenne. 4°. Geneve, 18C4. pp. 10- 8 Ann. Se. Nat. [5] Zool., x, p. 196. 



