. The Cambridge natural history. Zoology. 86 CRUSTACEA CIRRIPEDIA remarkable variation in the sexual constitution of some of the species. The great majority of the Pedunculata and all the Operculata are hermaphrodites, which habitually cross-fertilise one another, and this they are well fitted to do, since they all live gregariously and are provided with a long exsertile penis for transferring the spermatozoa from one to the other. In FiiUieipes, however, the individuals of which often live solitarily, it appears that self - fertilisation may occur. In Scalpelluvi. Fig. , Complemental ma
. The Cambridge natural history. Zoology. 86 CRUSTACEA CIRRIPEDIA remarkable variation in the sexual constitution of some of the species. The great majority of the Pedunculata and all the Operculata are hermaphrodites, which habitually cross-fertilise one another, and this they are well fitted to do, since they all live gregariously and are provided with a long exsertile penis for transferring the spermatozoa from one to the other. In FiiUieipes, however, the individuals of which often live solitarily, it appears that self - fertilisation may occur. In Scalpelluvi. Fig. , Complemental male of Scalpdhmi peronii, x 20 ; B, hermaphrodite imlividual of & vnlgare, x 2. a, Complemental males, in situ ; b, rostrum. (A, after Gruvel ; B, after Darwin.) three different kinds of sexuul constitution may occur: (1) According to Hoek in K Icdanoides, taken by the Challenger, the individuals are ordinary cross-fertilising hermaphrodites. (2) In the great majority of species, including the common S. vulgare, as originally described by Darwin, and since confirmed by Hoek and Gruvel,^ the individuals are hermaphrodite, but there are present affixed to the adult hermaphrodites, just inside the opening of the valves in a pocket of the mantle, a varying number of exceedingly minute males, called by Darwin "com- plemental ; These tiny organisms are really little more ^ Arch. Biol, xvi., 1899, p Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Harmer, S. F. (Sidney Frederic), Sir, 1862- ed; Shipley, A. E. (Arthur Everett), Sir, 1861-1927. ed. [London, Macmillan and Co. , Limited; New York, The Macmillan Company
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