No. I.] CONTRIBUTION rO INSECT EMBRYOLOGY. 1 21 



In a more advanced embryo (Fig. 49, Stage K) the male 

 ampullae have disappeared completely, and the tenth pair of 

 appendages, while growing smaller, have moved up to the inner 

 posterior insertions of the ninth pair. The ampullae have in- 

 creased in size and have come to lie at right angles to the lon- 

 gitudinal axis of the embryo. This causes the oviducts to 

 describe an arc. It is thus seen that the movement of the 

 female ampullae is essentially the same as that of the male, but 

 considerably weaker. Traces of appendages on the seventh 

 segment are still apparent. 



From this stage we may pass to a brief consideration of the 

 female embryo ready to hatch (Fig. 50). The ovaries {ov) 

 have now assumed their definitive characters. Although the 

 pointed and flattened ampullae have approached the median 

 ventral line, they are still separated by a wide space. Even in 

 this advanced stage slight thickenings of the integument over 

 the posterior edges of the ampullae may be taken to represent 

 the remains of the seventh pair of abdominal appendages. The 

 appendages of the tenth segment appear to have joined the 

 inner bases of the ninth pair. I must say, however, that my 

 observations on this pair of appendages are unsatisfactory, 

 notwithstanding I have taken considerable pains to follow their 

 history. The appendages of the eighth and ninth segments 

 undoubtedly form the two anterior pairs of gonapophyses. 

 The third pair has been described by Dewitz ('75) and others as 

 arising from the inner bases of the second pair and is therefore 

 supposed to belong to the ninth segment. I believe, however, 

 that the tenth pair of embryonic appendages persists and moves 

 forward to join the ninth pair, whence they grow out during 

 early larval life as the third pair of gonapophyses. In the 

 embryo the line separating the ninth and tenth segments is 

 certainly very vague, especially on the ventral surface, so that 

 the possibility of a fusion of the two pairs of appendages is by 

 no means precluded. That this fusion should occur is certainly 

 no more remarkable than the migration of the male ampullae 

 from the tenth to the ninth segment. Both of these forward 

 movements may be in some way connected with the forward 

 migration and fusion of the ganglia belonging to the eighth, 

 ninth, and tenth segments (cf. Figs. 42-46, ag'^-z). 



