314 
PROFESSOR ROLLESTON ON THE 
Observations on the Figures. 
Fig. 1. Shows the placenta of the Tenrec (Centetes ecaudatus) detached from the deci- 
duous serotina, shown in fig. 2, and from the utero-placental area covered with 
persistent or non-deciduous serotina, shown in fig. 3. Part of the amnios (a) 
and of the umbilical cord (uc) are left in connexion with the placenta (PL). 
The umbilical vessels are prolonged up into an upstanding rim of membrane, 
cu’, which is itself an upward prolongation of the chorion, and was con- 
tinuous with the uterine tissues along a parapet of membrane, v P, in fig. 3. 
Fig. 2. Deciduous serotina of Tenrec. It is separated both from placenta, fig. 1, and 
from the uterine structures figured in fig. 3. It is but of wafer-thickness, and 
centrally it has many perforations for the uterine vessels. In the natural 
condition of the parts its periphery would have been in connexion with the 
inner periphery of the circular area of corrugated mucous membrane seen in 
next figure, and one of its surfaces would have been in relation with the 
uterine aspect of the placenta, and the other with the foetal aspect of the 
persistent non-deciduous serotina, Ps, fig. 3. 
Fig. 3. Utero-placental area of Tenrec: uP represents the parapet of uterine mucous 
membrane with which the chorionic upgrowth (cu’, fig. 1) was continuous. 
Within this limitary line is a quoit-shaped area of mucous membrane con- 
centrically corrugated ; and within it again we have a space much perforated 
by orifices of blood-vessels, and covered with the non-deciduous or persistent 
scrotina, ps. The presence of the ring of corrugated mucous membrane 
bounding the non-deciduous serotina, and bounded itself by the circular 
parapet (u P) of mucous membrane, and the presence of an upgrowth of the 
chorion (cu’) continuous with this parapet, are phenomena, so far as is known 
by me, unique in the Mammalia. 
Fig. 4. Section of placenta (ex) with part of chorion (ca) of Guinea Pig (Cavia aperea). 
Upon the uterine surface of the placenta there is an upgrowth, pu’, the 
“Kern” of Bischoff (Meerschweinchen-Ei, 1852, pp. 43 & 44), the texture of 
which is to the naked eye somewhat looser than that of the larger mass, PL, 
of which it is morphologically and histologically but a part. In the angle 
between its outer border and the upper surface of the placenta is seen a small 
piece of membrane, F, which, in the natural state of the parts, was continuous 
with a process (@) of deciduous serotina, which is seen in the next figure. 
Near to the place of attachment of this process of membrane are seen the cut 
orifices of vessels belonging to the ‘‘ sinus circularis” system, for which see 
KOlliker, /. c. pp. 140, 147, or Robin, J. c. p. 130. 
Fig. 5. Section of the part of the uterine cornu and of the deciduous serotina which 
was in connexion with the placenta of the preceding figure. The deciduous 
