1898] NOTES AND COMMENTS 157 



facts are startling in themselves ; they are described luminously, 

 illustrated by beautiful figures, and they raise a number of novel 

 •questions. Mr Hill has been able to collect material consisting of 

 six stages — some from Perameles obesida, some from P. nasuta, but 

 the processes in the two cases he declares to be so similar that he 

 was able to take them consecutively without reference to specific 

 difference. The uterine wall prepares itself for the attachment of the 

 embryo in a fashion unknown in other mammals. In the normal way, 

 the mucosa hypertrophies ; the uterine glands enlarge ; the interglan- 

 ■dular connective tissue forms a loose network of cells permeated by 

 lymph and the blood-vessels enlarge. But the superficial epithelium 

 loses the outlines of its cells and becomes a syncytium, which 

 increases in thickness by the multiplication of nuclei and protoplasm, 

 ■and the blood capillaries penetrate the syncytial protoplasm until 

 they form a network upon and just under the surface. 



The embryo attaches itself to this syncytium by means of en- 

 larged ectoderm cells over the discoidal area of true chorion, with 

 which the allantois fuses. These ectoderm cells become resorbed, 

 4ind the allantoic capillaries grow down deeply into the syncytium 

 forming interdigitations with the maternal capillaries, the two sets 

 of vessels being separated only by their endothelial walls and a 

 little syncytial protoplasm. Thus a true, discoidal, allantoic 

 placenta is formed. It is non-deciduate ; at birth not only is there 

 110 loss of maternal tissue but an area of the allantois remains 

 attached to the syncytium, and gets absorbed by maternal leucocytes. 

 In addition to the allantoic placenta, there is a temporary yolk-sack 

 placenta, somewhat annular in character, and functional before the 

 allantoic placenta is ready. 



Mr Hill discusses the bearing of his discovery on the relations 

 between marsupials and Eutheria. He rejects the supposition that 

 the allantoic placenta of Perameles is a convergent but independent 

 structure. Like Semon and Hubrecht, he lays weight on the 

 functionless degeneracy of the allantois in marsupials generally, and 

 on the degenerate character of the milk dentition of marsupials. 

 He inclines to the belief that Eutheria and Metatheria are parallel 

 branches from a common stock, which possessed a discoid, allantoic 

 placenta. 



A Eresh Mammoth 



We learn from the Bevue Scientifiquc that Mr K. Nossilov, editor 

 of the Novoye Vremya, has discovered an entire mammoth in la-Mala 

 Peninsula in the country of the Samoyedes. In May 1897, he 

 arrived at the mouth of the river Jouribey, and learned that two 

 years previously the body of a mammoth had been found by the 



