31 



contiguous membrane. Adults, when quite wingless, are recog- 

 nised by the complete development of the genital appendages 

 and the much greater rigidity of their integument. 



The sternal segments of the thorax are almost concealed by the 

 broad, flat coxce, which are either concolorous, striped darker and 

 paler, or bordered by pale exterior margins. 



The Legs are strong, and all fitted for swift running, except in 

 the family Geoscapheusidw, in which the anterior pair is con- 

 spicuously modified for burrowing. The trochanters are usually 

 large, and the apex, in some cases, produced as a short spine. 

 The femora are much compressed, and either all simple or hairy, 

 or provided with two rows of longer or shorter spines on the inner 

 side, or, in a few instances ( Ataxigamia, Gynopeltis), the fore 

 femora alone are spined. The character of being thus armed or 

 not is used to divide the Blattaria^ into two main divisions. The 

 tihicB are either slender, incrassated, or, in Geoscaplieus, dilated 

 and flattened anteriorly, and are all armed with four rows of 

 spines, which are more or less developed, but afford no reliable 

 distinctions. The tarsi consist of five joints (one sometimes 

 obsolete), are slender and compressed ; each joint has usually a 

 pulvillus or pad beneath, while in some cases an arolium between 

 the two claws is present. The first joint is always the longest, 

 sometimes very long, and its comparative length distinguishes 

 some families or genera. 



The Abdomen consists of nine segments and the anal appen- 

 dages. The first segment is more or less obliterated and amalga- 

 mated with the metanotum, especially in the winged species, 

 while in the wingless it appears dorsally as a very narrow ex- 

 tended arc of a circle, projecting from beneath the hindmargin of 

 the metanotum, and does not attain the lateral margin. The 

 following six segments are well developed, their texture, colour- 

 ing, etc., and the form of their hind angles aftbrd some useful 

 specific distinctions. Tho eighth segment is usually entirely 

 covered by the preceding one, and only denoted laterally by its 

 produced posterior angles. The ninth is still more reduced, and 

 bears the articulated cerci and the supra-anal lamina between them. 

 The size, tfec, of the former supplies important characters for the 

 distinction of families, genera and species, while the latter is still 

 more important in this respect. On the ventral side the males 

 exhibit usually 7 — 8 zonal segments, the female six ; to the last 

 are appended the subgenital lamina with the styles of the males, 

 and the divided or united valvules of the females ; the genitalia 

 proper of both sexes are quite concealed by these organs, which, 

 in most instances, are very important for classification or ident- 

 ification. 



The ova are not deposited singly, but collectively in an egg- 



