152 MKilOIBS OF THE QCEEXSLAND MrSEUM. 



these are represented by squainiform lobes ; and I have previously showni that the 

 female of Escala circumducta ^^'alk. was erroneously described as a species of the 

 genus Loboptera Brunner. In this instance the females, having come to spend their 

 entire existence under the bark of trees, have almost discarded their organs of flight ; 

 whilst the males, only associated with them dining a brief pairing season, have 

 retained theirs. A similar sexual dimorphism obtains in tlie Panchlorine genus 

 Oniscosoma Brunner, the females of which are wliolly a])toroiis. whilst the males are 

 fully ^^•inged. Here both sexes may be found together under bark all the year lo.imd, 

 and I have never taken the male on the wing ; and both sexes are tj^ically depressed 

 insects. The same occiu-s commonly in the Epilamprlnte ; whilst in the Polyzosleria 

 group of the Blattina^ may be found every condition of the Hying organs, from the 

 fully spread tegmina and «ings of both sexes of Mclhana StSl, thi'ough tlie 

 quadrate tegmina and squamiform wings of Scabina Shelf., the quadrate 

 tegmina and absent wings of Temnelytra Tepper, the squamiform tegmina and 

 ab-sent wings of most species of Platyzo^teria Brunner and Cutili'a StSl, up to the 

 completely' apterous condition of the whole of Polyzosleria Burmeister, and many 

 species of Platyzosleria and Culilia ; some apterous species still showing in a faint 

 crumpling of the lateral ])arts of the me.sonotum and metanotum a vestige of the 

 unrequired and discarded organs of flight. !My experience of the Polyzosleria group 

 (with the exception of the genus Polyzosleria itself, of whose habits I am at present 

 in ignorance), and of the other .semi-apterous and apterous forms alluded to above, 

 leads me to the conclusion that all the known species are cryptic in their habits, 

 being found under fallen wood, under loose bark of standing trees, and in crevices ; 

 very seldom seen until their habitat is disturbed ; and that there is a definite correla- 

 tion between a depression of form and an absence of flying organs. 



In Panesthid there are in the one genus examples of the various stages in this 

 advance, from species with fully explicate tegmina and wings, to completely apterous 

 forms, with the addition of what appears to be an intermediate stage. I refer to the 

 condition which Brunner v. Wattcnwyl'^ writes of as an accidental mutilation foinid 

 in several species of Paneslhia. It has been y)rcviously suggested by ukv' that this 

 was a purposeful rather than an accidental abbreviation of the flying oi'gans, and 

 I look upon it as one of the early steps towards the discarding of organs of flight in 

 species whose modified ha})its no longer demand th(>ir ictention. The S(iuamiforiu 

 tegmina and wings would be a further stc]), and a condition to lie properly described 

 as vestigial rather than iiidimcntary. Dr. I{. .1. Tillyard informs me that no adult 

 fossil cockroaches arc known with abbicvlatcd organs of flight ; and it seems 

 probable that Mr. .Shclfoid' was light when he suggested, though on other grounds, 

 that our Polyzosleria gronp oi cockroaches, instead of being |iiiinitivc forms, aie on 

 the contrary very highly evolved. 



' Shaw: Victorian Nuturnlist, xxki, 7, 1914, p. 104. 

 ' Brunner: Nouv. SyHt. Blutt. ISOij, p. 391 et seq. 

 ' Sh.iw : Vict. Nut., xxxi, 7, 1914, p. 107. 

 ♦ Shilford : Trims, Ent. Soc. Lond. l'J09, p. 254. 



