The Male Genital Armature of the Dermaptera. 423 



The Protodermaptera fall into two groups, the Pygidicraniales 

 and Lahiduriales of Zacher, which I prefer to accept as Pygidi- 

 cranidse and Labiduridse ; they are perfectly distinct, yet it is 

 extremely difficult to tabulate the distinctions. Zacher bluntly 

 shirks the difficulty, saying that the groups are too hypothetical 

 and have too few concrete characters. Unfortunately, none of the 

 best characters lend themselves to sharply defining the two groups ; 

 if we take the presence of gonapophyses in the female, we are 

 obliged to separate the Pyraginte from their undoubted allies, the 

 Pygidicranine, and if we take the reduction of the telson, we are 

 similarly obliged to remove the distinctly Pygidicranine Echino- 

 somatinee into the Labiduridm. The manubrium also fails to help 

 us. In a general way, the head is flatter in the Pygidicranidtv, and 

 the femora are usually keeled and compressed. In the Labiduridse 

 the parameres are generally simpler, and the virga tends to have the 

 fine spiral structure referred to by Zacher as " Spiralversteifung," 

 and to have an inflated reniform vesicle at the base. In the 

 following table I have not ventured to dogmatize on the homologies 

 of the opisthomeres in the Labiduridie, and have left open the 

 question whether the large pygidium of Labidura contains the 

 metapygidium combined with it. 



We are, in fact, reduced to the inconvenient necessity of making 

 a lengthy explanation. If the female has gonapophyses, it certainly 

 is Pygidicranine, but all Pygidicranines have not gonapophyses, 

 e.g. the Pyragrinx ; we know at least that if we find gonapophyses, 

 there is no question of a Labidurid. Again, if all these segments of 

 the opisthomeres are present and separate, and the telson distinct 

 and chitinous, we know we have to do with a Pygidicranid-; one of 

 these two tests applied separately, and often both simultaneously, 

 will enable us to discriminate the two families. 



Table of Families. 



1. Gonapophyses $adsunt; aut, opisthomerum 3 seg- 



nienta separata, telsone perfecto • . .1. Pygidicranid.e. 



1, 1. Gonapophyses $ desunt ; opisthomerum saepius seg- 

 menta tantum 2 adsunt ; (interdum telson (?) 

 rudimentarium, membranaceum, adest.) . . 2. Labidurid.e. 



Family PYGIDICEANTD^E. 



Zacher deals with the group in considerable detail, but omits 

 to characterize it, and to discriminate it from the Labidur'vhr. 

 Verhoeff defines it in a restricted sense by the development of the 

 opisthomeres. 



If we limit it to those groups in which the telson is free, we 



