258 Dr. Malcolm Burr on the Opisthomeres 



Zacher maintains that the metapygidium fuses with 

 the telson, and not with the pygidium, and that the line of 

 demarcation is visible. I am not inclined to follow him. 

 It is difficult to understand his description, as he gives no 

 figures : he discusses the opisthomeres of Allostethus in 

 some detail. As I read them (see fig. 5) the broad basal 

 segment is the pygidium, the second, lobed segment meta- 

 pygidium and the transparent membrane represents the 

 telson. It is very noteworthy that the opisthomeres are 

 of quite different forms in the two sexes. Fig. 5 represents 

 the segments in the male, figs. 6 and 7 in the female and 

 in the nymph. 



In the Psalidae we can just detect the remains of the 

 telson, but the pygidium seems, in its construction and 

 pattern, to indicate a fusion of two segments : if that is 

 so, the first segment is the pygidium and metapygidium 

 united, the short transverse second plate the meta- 

 pygidium, and Zacher is right : if this is so, the telson has 

 no significance. 



In Verhoeff's formula for the Forficuline abdomen, his 

 eleventh tergite is the pygidium and metapygidium 

 united, and so should read 11 X 12, while the telson is the 

 thirteenth. 



In Kalocrania sp. we find the pygidium very broad at 

 the base, obtusely triangular, with a three-legged ridge 



Fig. 1. — Kalocrania, sp. (J. 



radiating from a central point, the apex of the posterior 

 ridge terminating in a rectangular lobe : the metapygidium 

 is quite separate, nearly rectangular, longer than broad, 

 but decidedly shorter than the pygidium : the telson again 

 is quite distinct, narrower than the metapygidium but 

 dilated at the apex, forming two rounded lobes separated 

 by a rounded emargination. 



