268 BRUES. 



of the lengths of the more anterior parts of the abdomen and the thorax. 

 In other genera {e.g., Scorpioteleia, p. 279) with similar parasitic habits, 

 the apical portion of the abdomen consists of long tubular slender 

 segments which telescope one within another, but remain movable 

 during life. In Dolichotrypes a precocious extrusion of the segments 

 at the time of pupation would lead to their chitinization and fixation 

 at whatever length they happened to have been protruded. I am 

 therefore inclined to believe that the polymorphic conformation of the 

 abdomen of the imago is actually determined by the individual insect 

 at the time it pupates and that the process is by no means an entirely 

 passive one. 



Nevertheless, the condition of the abdomen in Dolichotrypes recalls 

 the high and low males of other insects {e.g., certain Dermaptera and 

 lamellicorn beetles) well known to entomologists and subjected to 

 statistical study by Bateson, '92). That this dimorphism may be due 

 to Sporozoan parasites was suggested by Giard ('94), but however 

 plausible and attractive this hypothesis may appear, it seems, at least 

 in the case of the earwigs, to be disproved by the findings of Brindley 

 and Potts ('10) and of Brindley ('18) as these authors found no such 

 correlation between gregarine parasites and the high and low males of 

 Forficula auricularia. So far as Dolichotrypes is concerned such an 

 explanation undoubtedly cannot apply. I have been unable to find 

 any Protozoan or bacterial parasites in them and, moreover, as such 

 endoparasitic species do not have extensive opportunity to acquire 

 microorganisms they are never generally supplied with them, and stand 

 in marked contrast to the free living earwigs, termites, lamellicorn 

 beetles, et al. 



As already indicated, one of the species of Dolichotr^^jes and most 

 of those belonging to the other genera are new to science so that it has 

 been necessary to include a taxonomic account of these. This is given 

 below. 



Polymecus (Dolichotrypes) minor sp. nov. 



9 . Length 0.8 mm., exclusive of the 4th, 5th and 6th abdominal 

 segments; these together fully exserted 3 mm., and fully retracted 

 0.4 mm.; the hyaline 7th segment extrusible to 1.5 mm., rarely to 2.5 

 mm., filaments of ovipositor extrusible to 2 mm., rarely a little more. 

 Black, with the basal half of the scape, the coxae, and the legs, except 

 the thickened parts of the tibiae and femora, brownish yellow. Wings 

 entirely hyaline. Head, oval, fully twice as wide as thick, the occiput 

 more convex than the front; ocelli in a curved line, the lateral ones 

 one-half as far from the eye-margin as from the median one. Head 





