CONTRIBUTION TO INSECT EMBRYOLOGY. 159 



EXPLANATION OF PLATE VI. 

 {Xiphidium enstferzcm. Figs. 52-63 ; X.fasciat2im, Figs. 64 and 65). 



Fig. 52. Frontal section through first to fourth abdominal segments, show- 

 ing segmental arrangement of the gonads. Embryo in Stage F (Fig. 6, PI. I). 

 X 230. ml., longitudinal ventral muscle ; gd}gd?gd.,^ gonads of first, second and 

 third abdominal segments ; coe., ccelomic cavity ; ecd., ectoderm ; ep., epithelium. 



Fig. 53. Transverse section through the third abdominal segment of an 

 embryo in Stage F, (Fig. 6, PI. I). X 230. nc, nerve cord ; a7n., amnion, sms., 

 somatic wall of somite ; spins., splanchnic wall of somite ; v., yolk ; en., ento- 

 derm. Remaining letters as in Fig. 52. 



Fig. 54. Frontal section through the fourth abdominal segment of an embryo 

 in Stage F (Fig. 6, PI. I). X 230. The diverticula point towards the head, v., 

 yolk ; gd.,"" gonad of fourth abdominal segment ; coe., coelomic cavity ; ep., epithe- 

 lium. 



Fig. 55. Section through a somite from the third thoracic segment showing 

 a single enlarged germ-cell protruding into the coelomic cavity. X 230. 



Fig. 56. Sagittal section through the end of the abdomen of an embryo in 

 Stage G (Fig. 7, PI. I), tb., neuroteloblast ? ; nb., neuroblasts; coe.''-coc.,^° coel- 

 omic cavities of the seventh to tenth abdominal segments ; m.d., diverticulum of the 

 tenth abdominal somite which becomes the vas deferens and its terminal ampulla ; 

 gd.,'^° gonad in tenth abdominal segment (abnormal and atavistic); n.c., nerve cord 

 in unflexed portion of abdomen. 



Fig. 57. Transverse section through ninth abdominal segment of embryo 

 represented in Fig. 42, PI. V, cutting the tenth pair of appendages. X 175. msc, 

 muscular tissue ; prd., proctodeum ; n.c, nerve cord ; h., heart ; ecd., ectoderm ; 

 m.d., vas deferens; ta.in., terminal ampulla; ap.,^° appendage of the tenth ab- 

 dominal segment. 



Fig. 58. Transverse section of the abdomen of an embryo in the stage repre- 

 sented in Fig. 48, PI. V. The greater portion of the section passes through the 

 ninth, its anterior portion through the tenth abdominal segment. X 175. coe.,^° 

 coelom of tenth abdominal segment ; bl., blood corpuscle ; ta.m., terminal ampulla 

 of vas deferens ; m.d., vas deferens disintegratmg ; op.^ {ap.^°), third pair of gona- 

 pophyses ; n.c, nerve cord ; p}-d., proctodaeum ; ec, ectoderm ; h., heart. 



Fig. 59. Transverse section through the seventh abdominal segment, taken 

 from the same embryo as the section in Fig. 58. X 175. z/., yolk ; en., ento- 

 derm ; bi., blood-corpuscle dividmg ; h., heart ; coe.,'' coelom of the seventh 

 abdominal segment ; f.d., oviduct ; ta., terminal ampulla ; oe., oenocytes ; ec, 

 ectoderm ; nc, nerve-cord ; ap.,'' appendage of seventh abdominal segment. 



Fig. 60. Transverse section through the seventh abdominal segment of an 

 embryo somewhat older than that in Fig. 48, PI. V. X 175. ov., ovary; mc, 

 median cord ; ad., fat-body ; spms., splanchnic mesoderm. Other letters as in 



Fig. 59- 



Fig. 61. Sagittal section through the head of an embryo in Stage F (Fig. 6, 

 PI. I). X 175. y;^., frontal ganglion ; r.j^.,' first recurrent ganglion ; r.^.,^ second 

 recurrent ganglion ; v., yolk ; pc.,^ third protocerebral lobe ; ms., mesoderm ; lb., 



