Pakker. — Compound Eyes in Crustaceans 



PLATE YIII. 



Gonodacti/lu!>. 



Fig. 93. Part of a tangential section through a superficial portion of the retina. 



The extreme edges of the section both right and left are immediately 



beneath the corneal cuticula; the central portion is farthest from the 



cuticula. At the right of the middle line are seen the ends of the 



• larger ommatidia ; at the left, those of the smaller. X 275. 



" 94. A longitudinal section of a large ommatidium. The numbers at the left 

 of the figure correspond to the numbers of six figures of transverse 

 sections (Figs. 96-101), and mark the levels at which the latter were 

 made. Depigmented. X 275. 



" 95. A longitudinal section of a small ommatidium containing its natural 

 pigment. X 275. 



•' 96. A transverse section through the cells of the corneal liypodermis and the 

 distal end of the cone in a large ommatidium. X 275. 



" 97. A transverse section through the distal part of a cone in a large omma- 

 tidium. X 275. 



" 98. A transverse section through the middle of a cone from a large omma- 

 tidium. X 275. 



" 99. A tranverse section through a number of cones at the level of the distal 

 retinular nuclei in the large ommatidia. X 275. 



" 100. A transverse section through six retinulaj of the large ommatidia in 

 the region of the proximal nuclei. Each retinula is numbered. The 

 plane of this section is slightly oblique, so that retinula 1 is cut at a 

 relatively higher level than any of the others, and retinula 6 at the 

 lowest level. X 475. 



" 101. A transverse section of a retinula from one of the larger ommatidia, in a 

 plane not far from the basement membrane. Depigmented. X 475. 



" 102. A transverse section of a retinula from one of the smaller ommatidia cut 

 in a plane nearly corresponding to that of Figure 101. X 475. 



