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Show 278 MR. A. THOMSON'S REPORT O N T H E INSECT-HOUSE. [Mar. 28, the elements not directly related to the two digits (III & IV) were alone normally functional were in a backwardly developed state, as though they had been subjected to an arrest in growth. This was especially the case with the intermedium (i) and centrale (c). That the departures from the normal here met with admit of ready explanation on purely physiological grounds is sufficiently clear ; but the case is none the less interesting morphologically, as in those Urodeles possessed of numerically reduced digits both the reduction and fusion of all parts involved are invariably effected in a progressive manner from the post-axial or outer side inwards l and accompanied by a diminution in length of the outermost digit. Numerical variation of the digits is most marked among the Amphiumidae of all living Urodeles, the individual variations being such as to have led Cope to the conclusion2 that Amjmiuma tridactyla is but a variety of A. means, the digits of the species ranging from 1 to 3 in number in both fore and hind limbs. These facts, taken in conjunction with the recent discovery of a fleeting vestige of the pelvic member in one alone among a series of larvae of Ichthyophis glutinosa examined by the cousins Sarasin 3, show that individual variations of the kind herein recorded may realize (admittedly in a perhaps distorted form at times) the steps by which the reduction and loss of limbs have been effected in allied genera and species. March 28, 1893. Sir W. H. FLOWER, K.C.B., LL.D., F.E.S., President, in the Chair. Mr. Arthur Thomson, the Head Keeper, exhibited a series of Insects reared in the Insect-house in the Society's Gardens during the past year, and read the following Report on the subject:- Report on the Insect-house for 1892. Examples of the following species of Insects have been exhibited in the Insect-house during the past season:- Silk-producing Bombyces and their Allies. Indian. Attacus atlas. Anthercea myliita. cyntliia. Actias selene. pernyi. Cricula trifenestrata. roylei. 1 Cf. Baur,' Beitr. z. Morphogenie d. Carpus und Tarsus.' Th. I. Batrachia. Jena. 1888. 2 Proc. Amer. Phil. Soc. 1886, p. 526. Cf. also Hay, Amer. Nat. 1888, p. 315; and Cope, Batrachia of N. America, p. 218. 3 Ergebnisse Naturwiss. Forschung. auf Ceylon, Bd. ii. Hft. 2, p. 22. Wiesbaden, 1887 |