o 



04 Annals Entomological Society of America [Vol. XII,. 



In Forficula (Figs. 62-64) the eighth, ninth and tenth 

 abdominal tergites are fused, but their boundaries are clearly 

 defined. The eighth and ninth tergites are very short and 

 concealed by the much larger, overlapping seventh tergite; 

 while the tenth is also very large, doubtless owing to the great 

 development of the muscles concerned in the movement of 

 the large forcipate cerci. The eighth and ninth sterna are 

 concealed by the very large seventh sternum, and this feature, 

 together with the reduction of segments eight and nine and the 

 atrophy of the ovipositor is very suggestive of the ' ' Panisoptera 

 (Blattoidea, Mantoidea and Isoptera) ; but unlike these groups, 

 the tenth tergite does not replace the supra-anal plate, which 

 is entirely free, and although small, is heavily chitinized and 

 divided transversely into two separate sclerites, the distal 

 of which is situated ventrally between the bases of the cerci, 

 with which it is articulated. Possibly these two sclerites 

 represent the eleventh tergite and the true supra-anal plate, 

 as in the Acridoidea. Where three such sclerites are present 

 (Pygidicraniidae, Allosthetidce, teste Zacher) they have been 

 interpreted as representing the tergites of as many segments, 

 viz., the eleventh, twelfth and thirteenth, or anal segment 

 (pygidium, metapygidium and telson, or supra-anal plate), 

 but the evidence for the existence of an additional segment 

 between the eleventh and anal segments is quite insufficient. 

 It is worthy of note, however, that these three sclerites are thus 

 separately developed only in primitive genera. 



Apart from the features mentioned above, there appears to 

 be no evidence of close relationship between the Dermaptera 

 and the Panisoptera. 



The eighth and ninth sterna in Forficula are feebly chitinized 

 and each is divided into two lateral plates, which were con- 

 sidered by Verhoeff ('03)- to represent coxites. It is probable, 

 however, that this division of the sterna is related to the former 

 presence of an ovipositor, which occupied the median space, 

 and this view is supported by the presence of an ovipositor 

 in this situation in such genera as Kalocrania and Echinosoma, 

 as judged by Zacher's figures. In these genera the ovipositor 

 consists of but two pairs of valvulae, belonging to the eighth 

 and ninth segments. The former pair is long and slender 



22 Verhoeff, H. W. Nova Acta. Acad. Caes.-Leop., Vol. XXXI, 1903, pp. 

 277-278. 



