/2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL.98 



Fig. 33. Sagittal section through the head of a Ctenoccphalidcs felis embryo 

 showing the blind end of the stomodaeum at this stage. Below the 

 stomodaeum, the three fused ganglia of the gnathocephalon are 

 demonstrated. X 45». 



Fig. 34. Sagittal section through the stomodaeum of a Ctenoccphalidcs fclis 

 embryo. X 450. 



Fig. 35. Sagittal section through the proctodaeum of a Ctenoccphalidcs fclis 

 embryo at a stage somewhat younger than that from which figure 29 

 was made. X 450. 



Fig. 36. Portion of a section through a Ctenoccphalidcs fclis embryo at a stage 

 somewhat older than that from which figure 35 was made. The 

 proctodaeal invagination is considerably deeper in this stage. 



Plate 4 



Fig. 2>7- Section through the middle anterior region of a Ctcnocephalidcs felis 

 egg showing the male and female gametic nuclei fusing in syngamy. 

 Their peripheral processes are continuous with the reticular 

 protoplasm which ramifies throughout the egg. X 400. 



Fig. 38. Section through the middle anterior region of a Ctcnocephalides fclis 

 egg at a stage immediately following syngamy. The star-shaped 

 zygotic nucleus lies in the center of the field. The complete section 

 from which this enlargement was made is shown in figure 39. The 

 vitelline spheres and their enclosed vitelline bodies show very clearly. 

 X400. 



Fig. 39. Longitudinal section through an unsegmented egg of Ctenoccphalidcs 

 fclis showing the zygotic nucleus lying in the middle anterior region 

 of the vitellus. This nucleus is shown enlarged in figure 38. The thin 

 chorion of this species shows clearly in this section. X US. 



Fig. 40. Longitudinal section through a Ctenoccphalidcs fclis egg in the second 

 blastema substage of development. As is usual in early-stage prepara- 

 tions, the nuclei are only faintly visible. X H5- 



Fig. 41. Longitudinal section through a Ctenoccphalidcs fclis egg in the third 

 blastema substage of development, showing the nuclei "in the peri- 

 plasm. X 1 15. 



Fig. 42. Longitudinal section through the same egg as that from which figure 41 

 was made, showing three germ cells lying outside the egg at the 

 posterior pole. These cells are shown enlarged in figure 46. X n5- 



Plate 5 



Fig. 43. Posterior portion of a longitudinal section through a Ctenoccphalidcs 

 fclis egg prior to cleavage, showing the periplasm widened at the 

 posterior pole to form a distinct cap, the posterior protoplasmic cap. 

 X400. 



Fig. 44. Longitudinal section through the posterior region of a Ctenoccphalidcs 

 fclis egg in the first blastema substage of development, showing four 

 germ nuclei in the periplasm at the posterior pole. X 400. 



