284 MR. R. ASSHETON ON THE FCETUS AND [June 6, 



stated above, had been separated from the wall of the uterus, so 

 although shown in situ m the figure it must be understood that 

 the two parts were not together in my specimen. The line S 

 marks the boundary between the two. 



On the outside I have drawn in outline the muscle coats 

 (M) of the wall of the uterus. 



Within this, and seen only near the centre, is the trophospongial 

 tissue alluded to above (TS), while towards the peripheral parts 

 the thin layer of detritus can be seen at D, composed probably of 

 both maternal and foetal tissues. 



Text-fip'. 44. 



A section through the junction hetween trophoblast and trophospongia of Acomys. 



T. Trophoblast. TS. Trophospongia. EP. Pseudoepitheliuni of trophoblast. 

 EP'. Pseudoepitheliuni of trophospongia. MCH. Maternal blood. 



Everything within this line formed by the detritus layer on 

 the outside and the troj)hospongial layer at the centre is probably 

 fcetal in origin, except the maternal blood, which is exti-avasated 

 and flowing in channels excavated in the fcetal trophoblast. It 

 must of course be remembered that this description is an interpre- 

 tation of a single stage based upon the known facts in closely 

 allied forms (ref. Duval, Robinson, Jenkinson), and not upon the 

 study of the actual development in this genus. 



