5^ WHEELER. [Vol. VIII. 



by the envelopes, but as the growth of the appendages does 

 not cease, the arcs surrounding the hind legs gradually move 

 tailward. This movement is arrested just before the time for 

 hatching, when the antennae have grown to nearly twice the 

 length of the embryo. 



The mouth-parts and thoracic appendages have been gradu- 

 ally assuming their adult characters in the meantime. 



The pleuropodia, as described in a former paper ('90^), are 

 shed during hatching and just previous to that event may be 

 found attached to the pleural cuticle by means of very slender 

 pedicels. 



In the male the appendages of the 9th and nth abdom- 

 inal segments persist, the former as the stylets, the latter as 

 the cerci. In the female the cerci also persist but together 

 with them also the pairs on the 8th, 9th and loth segments 

 (Figs. 9 and 10 — op'^ {ap^)-opZ {ap^°). These are converted 

 into the gonapophyses. 



Apart from the eyes little pigment is developed in the hypo- 

 dermis during embryonic life, unless we regard as such the 

 brown granular secretion of the inner indusium. 



A number of eggs kept in the house the greater part of the 

 winter hatched May I5th-i8th, but I am inclined to believe 

 that out of doors the regular time for hatching is later, prob- 

 ably not till the end of May. XipJiidimn fasciatiun apparently 

 does not hatch till early in June, since I found larvae of this 

 species on Naushon Island June 9, which could not have been 

 more than a few days old. Inasmuch as the imagines of XipJii- 

 dium ensifermn oviposit on the average about Sept. ist, the 

 whole postembryonic development cannot occupy more than 

 three months. As this Locustid is monogoneutic, nine 

 months is therefore required for embryonic development. 

 Even if we deduct the period of quiescence due to cold 

 weather, it will still be apparent that the embryonic stages 

 must succeed one another very slowly in XipJiidimn as com- 

 pared with those of other Ametabola (e.g. Blattd), not to 

 mention the Metabola. 



