PLACENTAL STRUCTURES OF THE TENREC. 315 
serotina has been artificially displaced from its natural condition of apposition 
with the uterine wall’s non-deciduous serotina. It is still connected with the 
uterine tissues by blood-vessels (B v) and by tags or fimbriz, ps”, which pass 
from its periphery to become continuous with the uterine mucous membrane. 
From its concave surface there is a downward growth, ps’, which embraced 
the upgrowth (rt’, or ‘‘ Kern” of preceding figure), and which ends in two pro- 
cesses, one (p R) being the remnant of the decidua reflexa, and the other (c) 
having been continuous with F in preceding figure, and connected the deci- 
duous serotina with the placenta. The persistent non-deciduous serotina is a 
very thin layer, not separable as a distinct stratum to the naked eye from the 
circular muscular coat, c M; but it contains uterine glands. A wide interval, 
partly artificial, and containing many blood-vessels (pv), separates the circular 
from the longitudinal muscular coat, 1m. The mesometrium (m) is attached 
to the convex border of the figure 
Fig. 6. Decidua serotina, with remnant of reflexa, from aborted ovum of Guinea Pig 
(Cavia aperea), viewed from its placental aspect. It was found loose, and with 
nothing in connexion with it, in the uterine cavity of the individual whence 
the preparations for the two previous figures were taken. ‘Tags or fimbriz, 
ps’, by which it was attached to the uterine mucous membrane, proceed from 
its periphery. Two of these tags are prolonged inwards on its placental 
aspect to join the opposite poles of an inner raised circular cup, the decidua 
reflexa (DR). Within and at the bottom of this is a concentrically corrugated 
area of mucous membrane, which was thus thrown into folds for the reception 
of the placental upgrowth (rt’) of the ovum which was in connexion with it. 
The vessels which passed to the placenta made their way to it mainly by the 
depression in the centre of this area, c. (See Bischoff, Meerschweinchen-Ei, 
figs. 54, 55, 57.) 
Fig. 7. After-birth of Rabbit (Lepus cuniculus), showing the prolongations of the decidua 
serotina at either extremity of the structure, and their continuity with the 
uterine mucous membrane (um). ‘The placenta is obscurely seen to be made 
up of several (two or more) lobes, which are clamped together by a centrally 
constricted decidua serotina (ps), the constriction corresponding to the in- 
terval between the main divisions of the placenta. The decidua serotina has 
its long axis at right angles to that of the uterine cornu, to the mesometrial 
border of which it is, in this as in every other Rodent, attached. From 
either end a process is very usually, as in this figure, prolonged beyond the 
placental area to become continuous with the uterine mucous membrane on 
the free half of the tube, portions of which in this connexion are drawn at 
um in this figure. ‘These two processes represent the much more numerous 
ones (ps") of the Guinea Pig’s decidua serotina. Just fringing the lateral 
VOL. V.—PART IV. 27 
