7Ö^ . k. Ki8UI>'0tJYE. 



bearing t^egmeiit unite in the dorsal metlian line, the abdominal part 

 becomes ])ronnnent, as the yolk iö then forced into it and as the 

 epil;)la8t and niesohlast iiicreasing by rapid cell-division produce a pro- 

 jection (tigs. 15. 16). Tluis the abdomen comes to be distinguished 

 from the cephalotliorax. The y(jlk always ]-)lays a passive part. 



The peculiîiiity of the abdomen is that the yolk is found in the 

 later stages in the middle portion (rachis) only (figs. 54, 55), while 

 the cephaloth(3rax is entirely filled up with the yolk. In the abdomen 

 the epiblast with the enclosed mesoblast extends as two large wings (pi.) 

 on either side. In these wings there is no yolk. The coelom is also 

 not found in these wings. 



The appendages borne on the abdomen ditler greatly from those 

 on the ccplialothorax, remaining to the last as fiat, band-like ju'omi- 

 nences, compressed antero-posteriorly, and the two lateral members 

 afterwards iiiiiting more or less at the ventral median line (fig. 55). 



A Mille before hatchini«- the abdomen consists of ten se^-ments, 

 (tlic number e<ptal to tluit found in tlie adult animal) the four 

 anterior ones of wliich bear the appendages (fig. 56). 



Appendages. 



The fir^t rudiments of tlie appeiid.'iges a]>]tear in the stage oi' fig. 7. 

 J I is not righi to <"onsider the roiiiid jiroi iiberances foiuid in figs. 8, 9, 

 1(1. as the first rudiments of jqipendages, and the bases of the ])rotuber- 

 ances as the external extremities of tlie segments. A groove is produced 

 between every two segments. It is deeper towards the lateral ends. 

 Thus a [>air (,)f band-like prominences may l)e found in e\"ery segment. 

 Such a prominence is the rudiment ol' an a])pendage. When the 

 a!»iKMida<'>-e is tlius far formed, a i:'roove. the first lateral otoovc, 

 appears at the lateral i'd'^c <»f tlie segment on eaeh side (figs. 8, 9. 10. 



