224 ORTHOPTERA 



female the " lamina subgenitalis," or the " lamina subgenitalis 

 spuria," the concealed eighth plate being in this latter case con- 

 sidered the true subgenital plate. In the male this term is 

 applied to the ventral plate of the ninth segment, the corre- 

 sponding dorsal plate being called the " lamina supra-analis." 

 These terms are much used in the systematic definitions of the 

 genera and larger groups. 



The males, in addition to the cerci alluded to as common to 

 both sexes, are provided on the hind margin of the lamina 

 subgenitalis with a pair of slender styles. These are wanting 

 in the females, but in the common cockroach the young in- 

 dividuals of that sex are provided, like the male, with these 

 peculiar organs. j\I. Peytoureau has described ^ the mode of 

 their disappearance, viz. by a series of changes at the ecdyses. 

 Cholodkovsky, who has examined the styles, considers them 

 to be embryologically the homologues of true legs.^ These 

 styles are said not to be present in any shape in some species — 

 Uctobia, FanestJda, etc. ; this probably refers only to the adults. 

 In some cases a curious condition occurs, inasmuch as one of 

 the two styles is absent, and is replaced by a notch on the 

 right side, thus causing an asymmetry — Phyllodromia, Tmnnop- 

 teryx, etc. 



It has been found in several species that there are eight pairs 

 of abdominal spiracles, making, with the two thoracic, ten pairs 

 in all. The first of the abdominal spiracles is larger than the 

 others, and in the winged species may be easily detected by 

 raising the tegmina and wings, it being more dorsal in position 

 than those following, which are in some species exposed on the 

 ventral surface owing to the cutting away of the hind angles of 

 the ventral plates ; but the terminal spiracles are in all cases difii- 

 cult to detect, and it is possible that the number may not be the 

 same in all the species of the family. The cerci exhibit a great 

 deal of variety. In the species with elongate tegmina and wings 

 the cerci are elongate, and are like antennae in structure ; in 

 many of the purely apterous forms the cerci appear to be entirely 

 absent (cf. Fig. 130, Gromphadorhina), but on examination may 

 be found to exist in the form of a small plate, or papilla scarcely 

 protuberant. In the males of Hctcrogamia they are, on the 



' Bev. hiol. Nord France, vii. 1894, p. 111. 

 - Ann. Nat. Hist. Deer. 6tli, ser. x. 1892, p. 433. 



