. Essays on evolution 1889-1907. Evolution. MEMBRACIDS MIMICKING ANTS 259 prothoracic shield is modified into a resemblance to various objects, such as seeds, thorns, &c.—an excellent example of the parallelism between Mimetic and Protective Resem- blance pointed out in Section 3, p. 225. The effects pro- duced in the shield are at least as exact and detailed as those which in other cases are wrought in the form of the whole body. Thus, as Mr. W. F. H. Blandford has pointed out to me, a peculiar characteristic of certain tropical American ants (viz. the bead-like dilatation in the stalk of
. Essays on evolution 1889-1907. Evolution. MEMBRACIDS MIMICKING ANTS 259 prothoracic shield is modified into a resemblance to various objects, such as seeds, thorns, &c.—an excellent example of the parallelism between Mimetic and Protective Resem- blance pointed out in Section 3, p. 225. The effects pro- duced in the shield are at least as exact and detailed as those which in other cases are wrought in the form of the whole body. Thus, as Mr. W. F. H. Blandford has pointed out to me, a peculiar characteristic of certain tropical American ants (viz. the bead-like dilatation in the stalk of the abdomen) is reproduced in the shield of the Mem- bracid. This is well seen in Heteronotus irinodosus, shown in Fig. 6, copied from Canon W. W. Fowler's Monograph of the group in the Biologia Centrali-Americana. Finally, in the same group of Membracidae we meet. Fig. 7.—About three times the natural size. On the right is represented an immature Membracid {Rhynchota Homopterd) from British Guiana, which resembles an ant together with the leaf it is carrying. The latter is seen on the left, and represents the species Atta (Oecodoma) cephalotes from the same locality. The English leaf shown in the drawing is unlike the semi-circular fragments gnawed by the ant. (From Foulton, Proc. Zool. Soc. Zend., 1891, pi. xxxvi, fig. 2.) with another example which is also incapable of inter- pretation by any theory as yet brought forward except Natural Selection. An immature form of Membracid, with the prothoracic shield not yet formed, found by W. L. Sclater in British Guiana, strongly resembles one of the leaf-carrying ants which are so common in that part of the world; but the resemblance includes the leaf as well as the ant! The dorsal region of the Membracid is flat and compressed, so that it is as thin as a leaf; its border (the dorsal surface, which forms a sharp edge) is irregularly jagged as if gnawed, and during life it is green in colour. Beneath this leaf-like expanse the b
Size: 2189px × 1142px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookpublisheroxfordclarendonpre
