Dec, 1917.] CrAMPTON : ABDOMINAL SEGMENTS AND APPENDAGES. 227 



English designations '" suranal plate " and " podical plate " are hardly 

 suitablfe for universal application. In the following discussion the 

 designation suranal plate has therefore been changed to the briefer 

 term pygidimn, and for the designation podical plate, the briefer term 

 snbcc)-cns has been substituted, since the plate in question always bears 

 the cercus, as the latter name implies. 



The superorder Panplecoptera (composed of the Plecoptera, 

 Dermaptera, Hemimerus and the Embiids) is typically an ovipositor- 

 less group, although certain earwigs, such as the one shown in fig. 9, 

 have an ovipositor. In most members of this group, the -eighth ab- 

 dominal sternum does not overlap the following segment ; but in 

 certain Plectoptera there is a well-marked projection of the posterior 

 margin of the eighth abdominal sternum extending backward over 

 the succeeding sternum, and in many earwigs (fig. 9) the eighth 

 abdominal sternum overlaps the following segment ventrally to a con- 

 siderable extent. The tenth abdominal segment is relatively quite 

 large in this superorder, and in most Dermaptera, Plecoptera and 

 Embiids the pygidium (''11" of figs. 8 and 11) projects downward 

 from the end of the tenth segment ; although in the earwig shown 

 in fig. 9, the pygidium (labeled " 11 " in the figure) projects backward 

 and is curved in contour, somewhat like that of the Phasmid Timcma* 

 (Fig. 12, " II "). The cerci of some immature Plecoptera (fig. 4, c) 

 have small ring-like segments similar to those of the cerci of Lepis- 

 mids, while other Plecoptera (fig. 11) have cerci composed of cylin- 

 drical segments. In certain of the smaller Plecoptera, the number of 

 segments in the cerci is reduced to only two, so that the difference 

 in the cerci of the members of this superorder is not as great as 

 would at first seem to be the case, and indeed, certain Dermaptera, 

 such as Diplatys (or Dyscritina), in the immature stages have re- 

 tained segmented cerci very like those of the Plecoptera. 



The superorder Panorthoptera (composed of the Orthopteroid, 

 Phasmoid, and Grylloblattoid insects) is typically an ovipositor- 

 bearing one, and in this group, the ovipositor reaches its greatest 

 development (in the lower Pterygotan insects), being usually com- 

 posed of three valves (fig. 12, etc., d, i, and v), two of which are 

 borne on the ninth segment, while the ventral one is borne on the 



■1 An examination of subsequently received material would indicate that 

 the curved contour is due to being crushed. 



