1. The lateral eye shows one maximum in the ultraviolet and another in the blue-green region of the spectrum, probably attributable to two receptor types.

2. Light-adapted lateral eyes show the peculiar effect of a marked drop in ultraviolet sensitivity, irrespective of the colour of the adapting light.

3. Absorption by shielding pigment of the lateral eye is slightly selective in the short wavelengths.

4. The median eye has one maximum in the blue-green, violet sensitivity being apparent only with prolonged dark-adaptation.

5. Absorption by the shielding pigment of the median eye appears to be non-selective.

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