214 THE CANADIAN ENTOMOLOGIST. 



apparatus. The mentum is large, oblong or quadrangular, and inserted 

 in a sharply-cut opening of the head. 



Prothorax much narrower than head, long, enlarged behind, with sharp 

 straight side margin ; after the first third a transverse deep sulcus, mostly 

 prolonged behind along the side margin ; the part before the sulcus cor- 

 responds to the similar but broader part which covers the occiput in Ter- 

 mitina ; the hind part is a little convex ; a sharp impressed middle line 

 often runs along the whole prothorax. The mesothorax and the meta- 

 thorax are larger, quadrangular and about equal in the winged forms ; on 

 the tergum is a large triangular elevation, to the sides of which the hind 

 part of the wings is attached by a membranous fold. The tergum of the 

 wingless form is without this elevation, and among those forms the meso- 

 thorax may be larger than the metathorax. Each segment of the thorax is 

 divided into three parts. 



The wings are horizontal, of the same shape and size, long, nar- 

 row, three to four times longer than broad, rounded or elliptical at the 

 apex, as long as the abdomen, or somewhat longer in Olyntha (I have 

 seen no alcoholic specimens of Olyntha). The wings are not deciduous 

 as in Termitina, a basal squama being wanting ; indeed the wings are so 

 strongly attached that I have never seen a specimen dry or in alcohol 

 which had lost a wing. The attachment is made by the callus axillaris 

 anterior, just on the side of the anterior angle of the mesothorax, and by 

 the callus axillaris posterior a little behind the former and more dorsal ; 

 the membrane of the hind margin of the wings is firmly attached by a 

 membranous fold along the whole margin of the ob-triangular tergal ele- 

 vation ; the same attachment is found in Ephemerina, and is homologous 

 to the membranula accessoria of the Odonata. The callus ax. anterior 

 sends a strong vessel in the wing, forming the subcosta and the mediana ; 

 the callus ax. posterior sends from beneath in the wing the submediana 

 and the post-costa. I was not able to find tracheae in the wings or veins. 

 The costa, which is a real vein, originates from the subcosta ; the vein 

 along the hind margin can be followed mostly to the middle of the wing, 

 and originates from the post-costa. The membrane of the wings is more 

 or less rugose, similar to the wings in the group of Calotermes, including 

 C. verrucosus, pusillus, rugosus and related species. The rugosity is 

 effected by numerous little pits bearing a very small hair in the centre 

 they are more frequent and more densely placed on or near the veins, and 

 seem then to form a kind of socket ; a series of longer hairs is found on 



