STUDIES IN MAMMALIAN EMBRYOLOGY. 365 
by what others have found in the Rodents and the Chiroptera, 
&c., appear to be fatal to Turner’s views. 
They are: 
(1) In numerous mammalian orders ( Carnivora p. p., 
Fleischmann, Heinricius ; Chiroptera, van Beneden, Duval; 
Rodentia, Selenka, Masius, Duval, van Beneden; Insecti- 
vora, Hubrecht), among these the most primitive, the maternal 
epithelium of the uterus disappears at a very early moment at 
the spot where the blastocyst will adhere to the maternal 
tissue. 
(2) In the more primitive of these orders lacunary blood- 
spaces are in direct contact with the blastocyst at very early 
stages, even long before the embryonic area vasculosa has 
made its appearance. 
(8) The connection between these lacune and the maternal 
blood-vessels is brought about in a more indirect and more 
circuitous way than by a mere dilatation of capillary vessels, 
as was implied by Turner. 
(4) In the later stages foetal epiblast in varying thickness is 
present between the villi (omphaloidean or allantoic) of the 
blastocyst and this maternal blood. Im three of the four 
orders above named,’ this is the only tissue intervening 
between the maternal blood and the embryonic villus. 
I hope I have succeeded in furnishing the proof for these 
four propositions in the foregoing pages. 
In the preceding chapter (p. 338) the questions here 
referred to were already touched upon; in the following 
chapter I will indicate the more direct, though as yet hypo- 
thetical comparisons I desire to make between the highest 
and the lowest Monodelphia. 
In this review of the literature I have only to add that 
1 The order here excluded is that of the Carnivora. Heinricius’s results 
(‘Arch. Mikr. Anatomie,’ Bd. xxxiii), which have been published during the 
correction of this memoir for the press, leave room for a doubt whether a 
renewed investigation of the trophoblast in this order might not bring to 
light still closer degrees of correspondence than are as yet admitted by the 
latest authors, 
