17R T. THOMSON FLYNN 



vora, as suggested by Hubrecht and upheld by Assheton, 

 exhibit, of the Eutheria, the most undifferentiated arrange- 

 ment. The trophoblastic ' heaping up ' is common to the 

 allantoplacenta of lioth P e r a m e 1 e s and the Carnivora. 

 This is fundamental, and is sufficient evidence of the fact that 

 the cumulative type of placenta is the more primitive. 



8. Papers referred to in the Text. 



Assheton, R. (1006). — "The Morphology of the Ungulate Placenta, 



particularly the Development of that Organ in the Sheep, with Notes 



on the Placenta of Hyrax and the Ele])hant "", ' Phil. Trans.', Ser. B, 



vol. cxcviii. 

 (1909).^ — "Professor Hubrecht's Paper on the Early Ontogenetic 



Phenomena in Mammals : An Appreciation and a Criticism '", ' Quart. 



Journ. Micr. Sci.', vol. 54, part ii. 

 Caldwell, W. H. (1884).^ — " On the Arrangement of the Embryonic Mem- 



liranes in Marsupial Animals ". ibid., vol. 24. 

 (1887). — "The Embryology of IMonotremata and Marsupialia ",part i, 



' Phil. Trans.', Ser. B, vol. clxxviii. 

 Chapman, H. C. (1881).^ — " On a Foetal Kangaroo and its Membranes ", 



' Proc. Acad. Nat. Sci.', Phil., part iii. 

 Chipman, W. (1903).^ — " Obsei-vations on the Placenta of the Rabbit, with 



Esiiecial Reference to the Presence of Glycogen, Fat, and Iron ", ' Lab. 



Repts., Roy. Coll. Phys.', Edinburgh. 

 Ewart, J. C. (1917).^ — " Studies on the Development of the Horse. 1. The 



Develojmient during the Third Week ", ' Trans. Roy. Soc.', EdinTaurgh, 



51. 

 Grosser, O. (1910). — " Development of the Egg-membranes and Placenta ", 



in Keibel and ]Mall, ' Manual of Human Embryology ', Phil, and Lond. 

 Hartmann, C. G. (1916).- — " Studies in the Develo])ment of the Opossum, 



Didelphys virginiana, (i) History of the Early Cleavage, (ii) Formation of 



the Blastocyst ", ' Journ. of Morph.', vol. 27. 

 1919).^ — " Studies in the Development of the Opossum, Didelphys 



virginiana, (iii) Descrijition of new Material on Maturation, Cleavage, and 



Entoderm Formation, (iv) The Bilaminar Blastocyst ", ibid., vol. 32. 

 Hill, J. P. (1895). — " Preliminary Note on the Occurrence of a Placental 



Connexion in Perameles obesula and on the Foetal Membranes of 



Certain Macro])ods ", ' Proc. Linn. Soc.', N.S.W., vol. 10, ])art iv. 

 (1897). — "The Placentation of Perameles" (Contributions to the 



Embryology of Marsupialia, i), ' Quart. Journ. Micr. Sci.', vol. 40. 

 - — — (1899). — "On a Further Stage of the Placentation of Perameles and 



on the Foetal Membranes of Macropus parma "', ibid., vol. 43. 



