354 A. A. W. HUBREOAT. 
this it is my contention that a general name, equally applicable 
to the Trager of Rodents, to the epiblastic proliferation of the 
opossum, and to the feetal placentary tissue of Insectivora, 
Chiroptera, and Primates is for the present more useful than 
the application of special names that may hold good for sub- 
divisions in the foetal placentary tissue of some of these orders. 
The passage in Masius’ introduction (‘Archives de Biologie,’ 
vol. ix), to which I have just referred, runs as follows :— 
“ Hubrecht has described in the hedgehog (‘ Anat. Anz., 1888, 
No. 17) a considerable thickening of the epiblast in the whole 
circumference of the blastocyst, and that at very early develop- 
mentary stages. Maternal blood is said to penetrate into the 
lacunar spaces in the mass of this layer, to which he gives the 
name of trophoblast, and which plays an important part in the 
edification of the placenta. There is no question in Hubrecht’s 
note of a subdivision of the epiblast (trophoblast) into two 
strata, different both in structure and in further development. 
On the contrary, Keibel (‘ Anat. Anz.,’ 1888, No. 22) has just 
described this subdivision of the epiblast in. young blastocysts 
of the hedgehog. But, as he has no acquaintance with later 
developmentary stages, the author gives no indication whatever 
either of the reason or of the significance of this sort of 
delamination of the epiblast along the whole region of the 
embryonic area.” 
This statement of Masius is wholly misleading in so far as it 
implies : 
(1) That Keibel has noticed a subdivision of foetal epi- 
blast in the hedgehog which had escaped my attention. 
(2) That this subdivision noticed by Keibel is comparable 
to what was observed by van Beneden in the bat. 
On both these points Masius is in error, as 1 will now 
demonstrate: Ad 1. The divisions of the foetal epiblast into 
different layers is somewhat indistinctly described by Keibel 
(‘ Anat. Anz.,’ 1888, No. 22, p. 634) in the following words: 
“Tn the region of the germinal disc the blastocyst was three- 
layered, the embryonic shield consisting of two layers of epi- 
blast and of the hypoblast. At the border of the embryonic 
