Parker — Compound Eyes in Crustaceans. 



PLATE IV. 



Branchipus. 



(Figs. 30-32.) 



Fig. 30. A longitudinal section of an ommatidium. X 400 

 " 31. A transverse section through the distal end of four cones. X 400. 

 32. A transverse section through the middle portion of a retinula. X 400. 



Lnnnadia. 



(Figs. 33-39 ) 



Fig. 33. A section through the anterior part of the body, including the eye, in a 

 plane transverse to -the chief axis. X 25. 



" 34. An enlarged portion of a section from the same series as that from which 

 Figure 33 was drawn, but in a position slightly anterior to the lat- 

 ter. X 115. 



" 35. A section through the eye cut in the sagittal plane of the animal. De- 

 pigmented. X 90. 



" 36. A lateral view of an ommatidium. The numbers at the left of the 

 figure correspond to the numbers of the three following figures 

 of transverse sections, and mark the levels at which the latter were 

 taken. X 475. 



" 37. A transverse section through the corneal hypodermis and distal ends of 

 the cones. X 475. 



" 38. A transverse section through four cones at the level where they are 

 thickest. X 475. 



" 39. A transverse section through the central portion of four retinulse. X 475. 



Evadne. 

 (Figs. 40-45.) 



Fig. 40. An optical section through the eye and adjoining structures in a plane 



approximately parallel to the sagittal plane of the body, but lying 



somewhat to the right of it. X 140. 

 " 41. A transverse section through the distal ends of the cones. X 475. 

 " 42. A transverse section through the proximal end of a cone. X 475. 

 " 43. A transverse section through the distal ends of three groups of retinular 



cells. In each group the corresponding cells have been designated 



by the same number. X 475. 

 " 44. A transverse section through the central part of four rhabdomes. X 475. 

 " 45. A transverse section through a retinula. Depigmented. Kleinenberg's 



alum-ha?matoxylin. X 475. 



