530 A. A. W. HUBEECHT. 



area vasculosa is here not indicated; only its point of attachment is marked 

 by a thin line. 



Utr. Mus. Cat, n°' Sorex 100, 2 r. 1 *. 

 Fig. 35. — View of the inside of the uterus (in a stage corresponding to Fig. 

 44, which is somewhat further advanced than Fig. 14) after the mesometrical 

 half has been dissected away. The view is thus directed towards the inner 

 surface of the placenta. Three considerable allantoidean vessels, pressed in 

 between the amnion (which is not indicated in the figure) and the area vascu- 

 losa turned inside out (cf. Fig. 14), are seen to take their course towards a 

 central ring-shaped opening, through which they disappear. This ring is 

 the upper constriction of the trophoblastic annulus. The area vasculosa is 

 attached to it immediately below this rim. There is in the figure an irregular 

 lighter centre, and a darker outer circumference. The latter is continued on 

 the (here absent) inner surface of the mesometrical half. This darker colour 

 is caused by the special green pigment of the hypoblast cells of the yolk-sac. 

 Prep. Sorex n°' 77. 



Figs. 36 — 47. — Different phases of pregnant uteri of Sorex vulgaris 

 following on the earlier stages that were represented in vol. xxxi of this 

 Journal, PI. XXXVI (and following) figs. 13, 15, 43, 65, and 83. The 

 figures are natural size, drawn after the spirit specimens ; the catalogue 

 number between crotchets. 



Fig. 36.— Uterus, No. 101 (one of the swellings; cf. Figs. 60, 61,90— 92). 



Fig. 37. — Uterus, No. 106. a — h. The individual swellings, each of them 

 containing an embryo (cf. Figs. 10, 27, 76, 79, 84). 



Fig. 38.— Uterus, No. 61 (one of the swellings; cf. Figs. 14, 31, 58). 



Fig. 39.— Uterus, No. 130 (cf. 13, 30, 82, 85, 94). 



Fig. 40.— Uterus, No. 85 (cf. Figs. 12, 29, 81, 88, 89. 93). 



Fig. 41. — Uterus, No. 90 (one of the swellings). 



Fig. 42.— Uterus, No. 26 (one of the swellings; cf. Figs. 57, 59, 62). 



Fig. 43.— Uterus, No. 51 (cf. Figs. 8, 9, 26, 50, 55, 75, 11, 78). 



Fig. 44.— Uterus, No. 11 (one of the swellings ; cf. Figs. 33, 35). 



Fig. 45.— Uterus, No. 100 (one of the swellings; cf. Figs. 15, 32, 52— 54). 



Fig. 46.— Uterus, No. 80 (one of the swellings; cf. Fig. 86). 



Fig. 47.— Uterus, No. 3 (cf. Figs. 11, 28, 56, 80, 87). 



PLATE 35. 

 Figs. 52—54 enlarged X 200. Figs. 48—51, 55—65 enlarged x 260. 



Fig. 48. — First appearance of the trophoblastic annulus in a stage corre- 

 sponding to Fig. 6 (though not from the same preparation). About a dozen 

 cells in each section take part in the formation of the annulus. These cells 



