1883.] 



The Placentation of the Lemurs. 



279 



take a part in the nutrition of the foetus. The gland-layer of the 

 mucous membrane was readily distinguished subjacent to the crypt- 

 layer. 



The folds and crypts surrounding the smooth areas of the mucosa 

 were highly vascular. The crypts opened freely on the surface, and 

 to some extent smaller secondary crypts branched off from the larger 

 depressions. The distribution of the compact capillary network in 

 the walls of the crypts resembled the arrangement previously figured 

 in P. diadema. 



I drew the chorion away from the uterine mucosa by gentle traction, 

 and in the process of detachment the villi came out of the crypts 

 with great ease. A considerable area of chorion next the os uteri, 

 some of which had been torn in the descent of the foetus, was free 

 from villi and not very vascular. As one traced the chorion from the 

 os, short scattered villi in the first instance projected from it, to be 

 succeeded still farther away by longer and broader villi arranged 

 either in tufts or rows, the size and arrangement of the villi being 

 adapted to the crypts in the mucosa. Opposite the uterine opening 

 of the left Fallopian tube an area of the chorion about 33 mm. in its 

 longest diameter was smooth and free from villi : it was placed at 

 the end of the chorion furthest removed from the os uteri. A much 

 smaller non- villous area of chorion corresponded to the opening of the 

 right tuba, and was much nearer to the os than was the case with the 

 non- villous area opposite the left tuba ; in the right cornu the villi 

 were arranged in low ridges, and the ridges and furrows in the 

 uterine mucous membrane were shallow. Owing to the shortness of 

 the right uterine cornu, the chorion lodged within it formed only a 

 slight projection of the general bag of the chorion. Smooth patches 

 of chorion, in apposition with tbe corresponding smooth areas of the 

 mucosa, were interspersed aniidst the rows and tufts of villi which 

 covered so large a proportion of the free surface of the chorion. 



The blue injection which had been passed into the umbilical 

 trunks had filled the vessels ramifying in the deeper layer of the 

 chorion, which could be seen both in the villous and non-villous parts 

 of the membrane not unfrequently having a tortuous course. Opposite 

 the bases of the villi these vessels gave off small branches which 

 entered the villi and formed in them a close network of capillaries. 



The large sacs both of the amnion and allantois in L. xanthomystax 

 closely corresponded in arrangement with those previously described 

 by me in Lemur rufipes. 



The foetus was 19 cm. long from the tip of the nose to the root of 

 the tail, and the tail was 14 cm. long. It was evidently quite mature 

 and the hairs and nails were well developed. The lower incisors had 

 partially cut tbe gum. Both in this specimen and in the Propithecus 

 diadema previously described the breech was the presenting part, and 



