MORPHOLOGY OF COMPOUND EYES OF ARTHEOPODS. 157 



Fig. 7. — Cam bar us. This is introduced in comparison with the hypo- 

 thetical ommatidia. 



Fig. 8. — Callinectes. 



Fig. 9.— Talorchestia. 



In the last three forms no element corresponding to the central ganglion 

 cell of Limulus uor to the "hyaline cell" of Serolis can be found. The 

 sensory element of the ommatidium is represented by the retinulse {Rt.) only. 



Fig. 10. — Limulus. Diagram of the compound eye of Limulus, the 

 black, heavy line representing the ectoderm, and each depression in this layer 

 corresponding to an ommatidium. 



Fig. 11. — Serolis. In the same way as the above, the eye of Serolis 

 may be represented by a series of folds. 

 Fig. 12. — Notonecta. 

 Fig. 13. — Agrion (larva). 

 Fig. 14. — Branchipus. 

 Fig. 15. — Cambarus. 

 Fig. 16. — Penseus. 

 Fig. 17. — Lucifer. 



