Societies and Academies

Abstract

LONDON. Zoological Society, April 19. —Dr. S. F. Hartner, F.R.S., vice-president, in the chair.—Stanley Kemp: Notes on the photophores of decapod Crustacea.—J. Lewis Bonhote: Variations of Mus rattus, founded on an examination of the forms of that species found in Egypt. The author pointed out that on examination of the hind-foot measurements of a considerable number he found that the curve showed three distinct apices, and that two of these apices belonged, respectively, to the two forms found in Egypt, these forms being also more easily distinguished by their colour characteristics. The author in dealing with the rats of this species from the Oriental region had some years ago subdivided them into three subgroups, and it was now shown that the size of the feet typical of the three Oriental subgroups corresponded with the three apices in the curve of the Egyptian forms. He was inclined to think that these apices represented centres of variation, and were probably inherited as Mendelian characters, for were this not the case the smallest apex would have become swamped, and a regular curve would result. It was, however, evident that the small foot character was present and ready to become the dominant form in a very short time should conditions giving advantage to a small foot arise. On comparing the curve of the hind feet of Mus norvegicus, three apices were also observed, showing that in this species the “hind-foot character” was also present, but as there were no corresponding colour differences it was impossible to tell to which group any particular individual belonged. The author drew the following conclusion, viz. that there was considerable prima facie evidence that the size of the hind foot and the colour of the hairs on the underparts were Mendelian characters, and pointed out that the former character was also found in another species, Mus norvegicus, and the latter in a third species, Mus musculus. —G. E. Bullen: An example of posterior dichotomy in an Aylesbury duckling. A detailed account of a dissection performed on a duckling having supernumerary legs. In addition to a re-duplicated pelvis and the usual condition of the limbs presented in posterior dichotomy, it was found that the specimen showed evidence of a further re-duplication of the part dichotomised.