Cetacea. In the Cetacea, if we may generalize from Turner's observations on Orca Gladiator and the Narwhal, and those of Anderson (No. 191) on Platanista and Orcella, the blastodermic vesicle is very much elongated, and prolonged unsymmetrically into two horns. The mesoblast (fig. 160) of the allantois would appear to grow round the whole inner surface of the subzonal membrane, but the cavity of the allantois only persists as a widish sack on the ventral aspect of the embryo (_al_). The amnion (_am_) is enormous, and is dorsally in apposition with, and apparently coalesces with the chorion, and ventrally covers the inner wall of the persistent allantoic sack. The chorion, except for a small area at the two poles and opposite the os uteri, is nearly uniformly covered with villi, which are more numerous than in fig. 160. In the large size of the amnion, and small dimensions of the persistent allantoic sack, the Cetacea differ considerably from the Ungulata. [FIG. 160. DIAGRAM OF THE FOETAL MEMBRANES IN ORCA GLADIATOR. (From Turner.) _ch._ chorion; _am._ amnion; _al._ allantois; _E._ embryo.] Manis. Manis amongst the Edentata presents a type of diffused placenta[92]. The villi are arranged in ridges which radiate from a non-villous longitudinal strip on the concave surface of the chorion. [92] The observations on this head were made by Sharpey, and are quoted by Huxley (No. 202) and with additional observations by Turner in his Memoir on the placentation of the Sloths. Anderson (No. 191) has also recently confirmed Sharpey's account of the diffused character of the placenta of Manis. Manis presents us with the third type of placenta found amongst the Edentata. On this subject, I may quote the following sentence from Turner (_Journal of Anat. and Phys._, vol. X., p. 706). "The Armadilloes (Dasypus), according to Professor Owen, possess a single, thin, oblong, disc-shaped placenta; a specimen, probably Dasypus gymnurus, recently described by Kölliker[93], had a transversely oval placenta, which occupied the upper 2/3rds of the uterus. In Manis, as Dr Sharpey has shewn, the placenta is diffused over the surfaces of the chorion and uterine mucosa. In Myrmecophaga and Tamandua, as MM. Milne Edwards have pointed out, the placenta is set on the chorion in a dome-like manner. In the Sloths, as I have elsewhere described, the placenta is dome-like in its general form, and consists of a number of aggregated, discoid lobes. In Orycteropus, as I have now shewn, the placenta is broadly zonular." [93] _Entwicklungsgeschichte des Menschen_, _etc._, 2nd ed., p. 362. Leipzig, 1876.