16ri THE CANADIAN ENTOMOLOGIST. 



In the pallidus group I find another type of nymph very distinct in 

 the two species I have reared [pallidus, Ramb., at Galesbiirg, 111., May 

 1895 ; villossipes, Sel., Ithaca, N. Y., May 1897). 



The plagiattis and notatus groups of De Selys together present 

 another type of nymph, already pointed out by Hagen (loc. cit., p. 269) 

 as perhaps of more than subgeneric value. The bred nymphs of this 

 group are of plagiaius, Sel., 7iotatus, Ramb., spiniceps, Walsh, and 

 segregans, n. sp. (vid. sub finem.) 



Believing that the immature stages throw much light on the relation- 

 ship of the imagoes, and that the study of this large and homogeneous 

 group will be facilitated by the setting apart of distinguishable sub-groups, 

 I propose three new genera which need here have no further character- 

 ization than that of the following tables : Lanthus (XnvOavii contracted), 

 type G. parvu/us, Selys, Orcus (nomen proprium), type pallidus, Ramb., 

 and StyliTrus (frrrAo? and oi'/m), \.y[)Q plagiatus, Selys. With these apart 

 Gomphus is still somewhat polymorphic. The dilatatus group, character- 

 ized by extreme dilatation of the apex of the abdomen in the imago and 

 correspondingly greater width to the 9th abdominal segment in the nymph, 

 may yet, with advantage, be set apart. A clear line of demarcation, how- 

 ever, is not yet apparent. 



I now hazard a table for separating these subdivisions of the 

 Legion Gomphus, Selys. It is to be regarded as preliminary and 

 tentative, the more so as I have endeavored to base it on char- 

 acters common to both sexes. This legion is distinguished from 

 others of Gomphinne by the absence (normally) of cross veins from 

 all the triangles and supra-triangular spaces. 



Table for Imagoes of the Legion Gomphus, Selys. 



1. Outer side of triangle of fore wing distinctly angulated at the 



origin of the cross vein between the two upper discoidal 



areolets 2. 



Outer side of triangle of fore wing straight or nearly so j. 



2. Inferior abdominal appendages of S recurved upward in their 



apical half; vulvar lamina of ? shorter than half the 9th abdominal 



segment Herpetogomphus, Selys. 



Inferior abdominal appendages of ,^ recurved upward only at their 

 extreme apices ; vulvar lamina of ? almost equalling the 9th 

 segment ...,,,.,., Ophiogomphus, Selys. 



