34 RICHARD ASSHETON AND THOMAS G. STEVENS. 
EXPLANATION OF PLATES 1—5, 
Tllustrating Mr. Richard Assheton’s and Dr. Thomas G. 
Stevens’s paper, “Notes on the Structure and the 
Development of the Elephant’s Placenta.” 
CompLete List or LETTERINGS. 
A. Arterial vessel or placental afferent. dc. Blood cells (derived from 
maternal endothelium?). 47. Maternal blood corpuscle. cap. Capsule-like 
structure. co. Coagulum. cy. Syncytial layer—trophoblast. eyey. Syney- 
tium formed by fusion of two adjoining trophoblasts. ed. Endothelial-like 
cells. £.d. Foetal blood-vessels. fic. Foetal capillaries. f.v. Foetal villi. 
i. Deeply staining iron-containing tissues. Z.C. Large cells presumed to 
be of maternal origin. 7. Leucocyte. 7’. Leucocyte undergoing disintegra- 
tion. Me. Maternal cells. WW. C. H. Large maternal channel inter-cellular. 
m. ch. Small maternal channel intra-cellular. Mes. f. Foetal mesoblast. m. f. 
Nucleus of non-striated muscle fibres. 2%. nuclei. j/. plasmodial remnant. 
shr. Space caused by shrinkage. sh. v. short villus. s¢. v. Stem of villus 
broken off and presumably left in the walls of the uterus. Sw. cire. Sub- 
circular bodies of Owen. ¢r. Trophoblast (probably). U. Walls of the 
uterus. U.V.A. Uterine blood-vessel (arterial). U.V.V. Uterine blood- 
vessel (venous). V. Branched villus of non-deciduous border. V’. Villus 
of deciduate portion. V'’. Villus of zonary belt which penetrates into the 
walls of the uterus. 7''’, Minute villi on the chorion beyond the zonary 
belt. w. Non-cellular wall of the maternal blood-channels. «. Point of 
communication between the maternal blood-channels of region B inside the 
space of region C. z. Layer of homogeneous material containing degenerating 
nuclei of trophoblastic origin. zz. Layer of homogeneous material containing 
no trophoblastic nuclei, but occasional rounded cells (of maternal origin ?). 
PLATE 1. 
Fie. 1 a—A diagram of a section through the full-term zonary placenta of 
an elephant to illustrate the relative position of the several regions A—D. 
Region A is the chorion from which villi pass towards the walls of the uterus. 
Some pass through the whole thickness of the after-birth, others only extend 
a short distance. Region B, which forms the great bulk of the after-birth, 
is made up of feetal villi and channels containing maternal blood. Region C 
is a much looser layer in which the fcetal villi are lying freely in irregular 
blood-spaces. There are no walls to these blood-spaces. This region is 
traversed by a few blood-vessels which carry blood probably towards the 
