72 THE BLATTIDAE OF PANAMA 



lowlands of Costa Rica, about ten miles up the Rio Pirris.^"^ 

 This optimum type probably represents an incipient geographic 

 race, but as yet has not reached a sufficient degree of differentia- 

 tion to warrant nominal recognition. 



That the present insect, though not domiciliary, thrives about 

 human habitations under litter of all kinds, must be considered 

 in studying material. It is this factor which increases the possibil- 

 ity of specimens being found adventive and not peculiar to the 

 locality at which they were secured. 



The concealed male genitalia in this species are very complex. 

 The genital hook is simple, the titillator specialized distad (plate 

 IV, fig. 9), this specialization more decided in riifa debilis Hebard 

 and ruja occidentalis than in ruja rufa. The paired plate beneath 

 the supra-anal plate is highly specialized on both sides, developed 

 into chitinous lobes and shafts, of which the sinistro-dorsal shows the 

 greatest specialization. The usual development of this shaft is here 

 shown (plate IV, fig. 10). Individual variation occurs in which one 

 or both of the marginal teeth disappear, and in ruja occidentalis the 

 shaft occasionally is much broader, or much more elongate and 

 slender. In rufa occidentalis the ventral surface of the supra-anal 

 plate frequently bears a large, irregularly rounded, mesal lobe cov- 

 ered with stiff bristles, or is unspecialized as is normal in ruja rufa. 

 These features of variability in the male concealed genitalia are a 

 very unusual occurrence in the Blattidae. 

 Ischnoptera gatunae^^^ new species (Plate IV, figure 11.) 



The present species belongs to a group of elongate, light brown 

 forms, having the latero-caudal sulci of the pronotal disk well 

 developed and in some of the species distinctively colored. This 

 group we would call the Gatunae Group; it apparently follows 

 the Rufa Group and precedes the Apolinari Group in linear position, 

 the latter coming before the second section of the genus, which 

 includes a number of groups of relatively much smaller species. 



i°i For a discussion of this material and the variability of this race, see Hebard, Trans. 

 Am. Ent. Soc, xlii, p. 354, (1916). 



'"^ The material of this species was taken on the Rio Trinidad, in an area now Hooded 

 by (iatun Lake. 



