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Show 960 MR. W . A. FORBES ON THE INCUBATION [Nov. 29, 6. Observations on the Incubation of the Indian Python [Python molurus), with special regard to the alleged Increase of Temperature during that process. B y W . A. F O R B E S , B.A., Prosector to the Society. [Received September 27, 1881.] The first exact observations of the incubation of their eggs by the females of the constricting Serpents included in the genus Python were made, forty years ago, by M. Valenciennes in the Jardin des Plantes at Paris, his account having been published in the 13th volume of the ' Comptes Rendus' for 1841 l. In this case the species observed was Python bivittatus : a female, about 10 feet long, which had been in company with a male of the same species of rather smaller size, and with which she had been seen several times in copula, laid at the beginning of May fifteen eggs, round which she coiled herself up, and so remained for fifty-six days, when eight of the eggs hatched, producing young snakes about half a metre in length. During the period of incubation Valenciennes observed a marked increase of temperature in the female, highest at the commencement of incubation and gradually diminishing thence till its close. His observations on the temperature are recorded in a table appended to the memoir already cited ; and to them I shall have further occasion to refer in the sequel. In the year 1862, a large female Python seba laid a number of eggs, and also incubated on them, in this Society's Gardens, as described by Mr. Sclater at length ~. The period of incubation lasted 82 days; at the end of that time the eggs were removed, as none had hatched, and they were evidently decomposing. On examination five or six were found with embryos inside, one of these being eleven inches in length. A few observations on the temperature of the female were taken, that of the male in the same compartment being taken at the same time. In every case, the female was found to be several degrees warmer than the male, the difference ranging between 20,8 F. and 120,4 F. when the surface temperature was recorded, and between 60,8 F. and 20°*0 F. when that between the folds of the animals was measured. During the past summer we have again had an opportunity of observing the incubation of a Python in the Society's Gardens. A female Python molurus, about 12 feet long, which had been living in company with two somewhat smaller males (one of this species, the other being a Python Bivittatus), deposited during the night of June 5th-6th a number of eggs, about twenty. Round these she coiled herself up, in the same way as already observed by Valenciennes and Mr. Sclater, the eggs being nearly entirely concealed from view by her folds. In this position she remained for six weeks, without once eating, and with only one break in her 1 Tom. cit. pp. 126-133. * P.Z.S. 1862, pp. 365-368. |