l^OilTAL MEMBKANES OF CHIROMYS MADAGASCARIENSIS. 1145 



-51. The Foetal Membranes and Placentation of Cldromys 

 viadagascariensis . By Professor J. P. Hill, F.R.S., and 

 R.H.Bqrne, M.A. (With an Appendix on the External 

 Characters of the Foetus, by R. i. PococK, F.R.S.) 



[Received October 24, 1922 : Read October 24, 1922.] 

 (Plates I.-YI.* ; Text-figures 1-6.) 



The structure of the foetal membranes and placenta of the 

 Lemurs was first made known during the years 1871-1877 by 

 the researches of A. Milne Edwards (1, 2, 3) and Sir William 

 Turner (5, 6). Contrary to the prevailing belief, the placenta 

 was shown to be of the non-decidua,te diffuse type, quite unlike 

 that of the Apes and Man, and more nearly resembling that of 

 certain Ungulates, particularly the Pigs. 



The species examined at that time belonged exclusively to the 

 subfamilies Lemurince and Indri since, of Madagascar, but in 1884 

 a brief description of the foetal membranes of the remarkable 

 Madagascar Lemur, Chiromys, was published by Milne Edwards 

 (4), and twenty-five years later Hubrecht (10) reproduced a 

 photograph of the surface of the chorion of a fcetal specim.en of 

 the same in the collection of the British Museum and now in 

 onr possession (our specimen B). 



In 1894 our knowledge, hitherto confined to the Madagascar 

 species of the order, was extended to the Lemui's of the Old 

 World by the preliminary description by Hubrecht (8) of pregnant 

 uteri of Nycticehus tardigraclus and Tarsius 8])ectr%mn. He 

 showed that in the fi]-st-named species the placenta conformed, 

 with some minor though characteristic differences, to that of the 

 Madagascar Lemurs, but that the placenta of Tarsitis was quite 

 difi'ei-ent, and i-esembled that of the Apes and Man in being dis- 

 coidal and deciduate. In a later paper (9) Hubrecht gave a 

 more detailed account of the development of the placenta of 

 Tarsius, but no further description of that of Nycticebtis has 

 appeared. In 1902, however, our knowledge of the placentation 

 of the Lorisiformes was further extended by the publication of a 

 lengthy paper by Strahl (14) on the placenta of the African genus 

 Galago, wherein it is shown that Gcdago, in tlie details of its 

 placentation, agrees more closely Vv'ith Nycticehus than with the 

 Madagascar Lemurs, as was to be expected. Strahl in a. subse- 

 quent paper (15) and more recently Jenkinson (16) have added to 

 our knowledge more especially of the histology of the placenta of 

 these latter forms. 



The foetal membranes and placentation have now been described 

 in more or less detail in representatives of all the existing 

 families and subfamilies of the two groups of the true Lemurs — 



* For explanation of the Plates, see p. 1169. 



