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Show 1 9 0 5 .] IN THE BEETLE GONIOCTENA VARIABILIS. 5 3 3 larvae which hatched yielded this form, it probably replaces the other varieties altogether. A possible explanation of the meaning of this seasonal change occurred to me, when I noticed that the plain green form only appeared when the bushes began to come into bloom. Bateson has pointed out how close a resemblance the green striped form lias to the grey-green of the Spartium twigs, and suggested that the resemblance might be regarded as protective. So also the red spotted type has a marked general similarity to the common Coccinella septempunctata which frequently occurred on the Spartium ; so that the red type of coloration may perhaps be considered as mimicry of a species protected by its unpleasant odour. But more close than either of these is the resemblance of the plain green type to the flowers of the Spartium. The flowers are very small and grow in clusters ; the petals are yellow, but are partly covered by the bright green calyx. When a bush is in full bloom the plain green type of beetle becomes almost invisible ; its thorax is yellow corresponding with the yellow petals, and its elytra have nearly the same colour as the calyx. The general resemblance is so close that the beetles are very hard to see when the bush is in bloom, although when they are found on a plant which has not come into flower they are nearly as conspicuous as the red type. My observations, taken as a whole, lead me to the conclusion that the correlation between the two main forms of Gonioctena and the two sexes, which Bateson observed at Granada, is a special phenomenon depending partly on locality and partly on season. At Honda the correlation was much less conspicuous, and at Malaga it did not exist. Further, it appears that the frequency of the different varieties depends largely on season, but my observations did not extend over a long enough period to work this out thoroughly. At the higher, and presumably more backward, localities the males were more numerous than the females, and the red spotted type was most abundant; this was most conspicuously the case in Bateson's collections from Castillejo. Near sea-level there was an excess of females, and at Palo this was associated with a predominance of green. Finally, as the season advanced and the Spartium came into bloom, a pure green type appeared; and from the fact that no other form hatched from the larvae which I collected, it seems probable that in the summer this is the predominant type of both sexes. In conclusion, I wish to acknowledge my indebtedness to my brother for much valuable help in collecting the beetles. Zoological Laboratory, Cambridge, July 1905. |