No. 1.] EVES OF ARTHROPODS. rSy 
of the retina. In this respect also, Grenacher’s figure is incor- 
rect, since it represents a broad layer of long upright rods, 
whereas no such structures are present. 
The eye of Hydrophilus, as shown in the woodcut, is much 
like that of eyes II. and IV. of Acilius, even to the presence of 
the large retinal cells at the bottom of the furrow. 
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Figure 4.—Uorizontal (4) and vertical (2) section of the larval eye of a 
neuropterous larva, Chauliodes (?). cg. corneagen; /1, 72, inner and outer lenses; 
o. w. outer wall of the optic vesicle; +d. rods. 
Figure 5.— Diagrammatic views of the retinidial fibrille in upright and horizon- 
tal rods. A. cross section of rods of Pecten,; B&B. same of small horizontal rods of 
Acilius ; C. same of large rods, and D. longitudinal section of upright rods in eye V. 
The arrows indicate the direction of the light. 
In Fig. 4 is shown a section through the eye of what I took 
to be a full-grown larva of Chauliodes, but I am by no means 
certain that it is such. Expecting to obtain more material, 
all but the heads were thrown away, and now I have no means 
of identifying the larvee. 
I have represented a section of the eye because it showed an 
interesting modification of the three-layered ocellus. There 
seem to have been present both upright and inverted retinal 
cells, as in eyes V. and VI. of Acilius, but the latter, instead of 
retaining their inverted rods have converted them into a cuticu- 
lar, nerveless mass that has assumed the function of an inner 
