316 PROF. ROLLESTON ON THE PLACENTAL STRUCTURES OF THE TENREC. 



borders of the decidua serotina, along which the uterine mucous parapet was 

 continuous with it, and passing underneath its two prolongations, d s", is seen 

 the decidua reflexa, which is rudimentary in the Leporidse. 



Fig. 8. Vertical section of uterus of Rat {Mus decumanus) through utero-placental area, 

 after parturition. The letters u p show the line where the non-placental 

 uterine mucous membrane became continuous with the decidua serotina 

 which was discharged with the after-birth. The persistent non-deciduous 

 serotina, which is inseparable from the circular muscular coat, forms a hernia- 

 like protrusion out of, and not corresponding with, the curve of the uterine 

 walls. A funnel-shaped depression leads down to it, and a lateral diverti- 

 culum is thus appended to the uterine tube. The persistent serotina (p s) and 

 the circular muscular coat (c m) with which it is mixed up, filling up its inter- 

 stices, is separated by an interval (bv), a little widened artificially, from the 

 longitudinal muscular coat (lm). The non-placental mucous membrane is 

 much corrugated, owing to the contraction of the previously distended uterus. 



Fig. 9. Part of placenta, deciduse, and uterine walls of Pig-tailed Monkey {Macacus 

 nemestrinus). The placenta (pl) has been artificially separated from the utero- 

 placental area, and is kept in connexion with the uterus by a pointed process 

 abutting upon its uterine aspect, and consisting of decidua vera, persistent, 

 and deciduous serotinse. A thin lamina of membrane (d s) is seen in the 

 intervals between the placenta and the utero-placental area, being one part of 

 the decidua serotina, tougher, more coherent, and more separable in this 

 Simious than in the Human placenta. The persistent serotina (ps) is loosely 

 reticular, but limited towards the placenta by a smooth horizontally lying 

 membrane, which would probably have been deciduous. The decidua reflexa 

 (d r) is represented by a layer on the chorion (cu) : it is separated by a wide 

 interval from the non-placental uterine mucous membrane (u m), which might 

 perhaps not have been deciduous (see Virchow, Qesamm. Abhandl. p. 782) . The 

 " Decidua- Fortsatze" are well seen in the section of the placenta, as in the 

 Human placenta at six months. (Cf. Schroder van der Kolk, cit. Priestley, 

 /. c. p. 57, fig. 16, or Kolliker, /. c. pp. 148, 177, 183, and Ecker's ' Icones 

 Physiologicae,' tab. 28. fig. 1, df.) 



