600 
MR. B. T. LOWNE OR THE MODIFICATION'S OF 
Fig. 7a. A transverse section immediately below the cornea of the eye of Formica rufa. 
Fig. 8. Transverse section through the rod cells of the eye of the Wasp. 
Fig 8a. A transverse section through the stemonata of the eye of F. rufa. 
(Figs. 9 to 13, inclusive, are in Plate 53.) 
Fig. 14. The chamber from the eye of the Blowfly. 
Fig. 15. The rhabdia of the same. 
Fig. 15a. A portion of one of the rhabdia of the same. 
Fig. 16. Transverse sections through the rhabdia of the same. 
a and b. Compound rhabdia. 
c and d. Simple rhabdia. 
Fig. 17. The inner extremities of the rhabdia and the nuclear masses of pigment seen 
from the retinal surface of the rhabdia. 
Fig. 18. The rhabdia and chambers of Tabanus, from a dried insect. 
Fig. 19. A portion of two rhabdia from the same. 
Fig. 20. The chambers of the eye of Tabanus. 
The details in all the figures are drawn with a Nachet yg-th immersion. 
PLATE 53. 
Fig. 9. Section through one of the elements of the compound eye of Eristalis. 
Fig. 9a. Four facets of the cornea, showing Semper’s nuclei. 
Fig. 10. Details of the compound eye of Eristalis. 
a. Transverse section through the tetrasome. 
b. Transverse section immediately below the tetrasome. 
c. Section through the lower end of one of the rhabdia from near the 
periphery of the eye. 
d. Section just above the pigment cells of the rhabdion. 
e. Section just below the pigment cells. 
f g, and i. Sections through the rhabdia. 
h. Lower end of one of the rhabdia, with six pigmented nuclei from 
near the periphery of the eye. 
Jc. Section through a facellus from the facelloid layer of the retina. 
1. Lower end of a compound rhabdion from near the outer edge of 
the eye. 
Fig. 11. A portion of one of the triquetrous rhabdia. 
Fig. 12. Lower end of the rhabdia to show their connexion with the nervous retina. 
Fig. 13. The nervous retina of Eristalis. 
Fig. 21. Two chambers from the eye of Agrion virgo. 
Fig. 21a. Four facets from the same eye seen from the outer surface. 
Fig. 22. A portion of one of the rhabdia. 
