THE CANADIAN ENTOMOLOGIST. 247 



device at ihc i.nd of ilic abdunieii ihat conveys the air to its destination. 

 Here, liowever, the similarity ceases. While in the adult the siphon is as 

 previously described, in the nymph this bisectional tube is replaced by an 

 involution of what may be the seventh abdominal segment, which is rolled 

 up and has an open joint beneath, the edges being fringed with hairs. 

 The sides of the abdomen are folded under, covering the inferior part of 

 the abdomen on each side to within a third of the distance to the keel, 

 which is fringed with hairs, as are the bent-under abdominal edges. 

 These bent-under edges are continuous with the rolled siphon. Under 

 these edges, in the channel thus formed for the passage of air, lie the 

 functional .abdominal spiracles. The false stigmata appear as dark thick- 

 enings of the dorsal integument, but show no opening or internal 

 connection in the nymph as pointed out by Martin (op. c). The edges of 

 the folded-over connexivum are indented under the darkened areas. The 

 abdominal spiracles are plain circular openings, to which the tracheae run. 

 They present no peculiar features. Owing to lack of material, and partly 

 to the great difficulty in dissecting nymphs satisfactorily when in the fifth 

 instar on account of the formative processes then so actively at work, it 

 has not been possible to demonstrate the thoracic spiracles. This is 

 reserved for another occasion. 



The detailed life-history which follows is lacking in many particulars, 

 but this was in a great measure unavoidable, as my material in some of 

 the instars consisted only of the cast larval skins. These are in many 

 ways very good for showing details of structure, but owing to their 

 extreme thinness it is at times impossible to mount them satisfactorily. 



Ovum. — Shape : Imperfectly oval, flattened at the upper end, from 

 which arise two long thread-like processes, longer than the ovum and 

 thickened at the base, diminishing in thickness toward the apex. 



Size: Long., 3 mm.; lat., i mm.; appendages, long., 5 mm. 



Colour : White at the base, growing dark toward the apex ; when 

 freshly deposited clear white. 



Markings : Surface of chorion thickly covered with irregularly 

 circular pits, in the middle of which is a point. The processes appear 

 smooth. 



The egg of Ranaira^ together with that of JVepa, has long been a 

 favourite subject for study, owing to the alluring peculiarities of structure. 

 Entomological works invariably refer to its bifilamented condition, 

 especially to that of ^. iinearis, L., on which all the studies and experi- 

 ments to date have been made. Shuckard, in his translation of 



