471 



attention to the important anatomical characters which separate the 

 articulated Brachiopoda as a group from the inarticulate division. 



In conclusion, the author draws a parallel between the Brachio- 

 poda and the Polyzoa, demonstrating the close structural conformity 

 between these two groups. 



II. " On the Placenta of the Elephant/' By Professor RICHARD 

 OWEN, F.R.S. &c. Received April 1857. 



(Abstract.) 



In this paper the author gives a description of the foetal mem- 

 branes and placenta of the Indian Elephant. The chorion forms a 

 transversely oblong sac about 2 feet 6 inches in long diameter, en- 

 compassed at its middle part by a placenta of an annular form, 2 feet 

 6 inches in circumference, from 3 inches to 5 inches in breadth, and 

 from 1 inch to 2 inches in thickness ; in structure resembling that of 

 the annular or zonular placenta of the Hyrax and Cat. The part of 

 this placenta which had been detached from the maternal portion 

 occupied a narrow annular tract near the middle line of the outer 

 surface. A thin brown deciduous layer was continued from the 

 borders of the placenta for a distance varying from 1 to 3 inches 

 upon the outer surface of the chorion. Flattened folds of a similar 

 layer of substance, or false membrane, could be raised from some 

 parts of the surface of the placenta ; at other parts the substance 

 formed irregular fibrous bands, the fibres extending in the direction 

 of the circumference of the placental ring. The outer surface of the 

 chorion is for the most part smooth and even shining, but at each 

 of the obtuse extremities of the sac there was a villous subcircular 

 patch, between 2 and 3 inches in diameter, the villi being short and 

 graniform, th of a line in diameter or less. Thus the chief points 

 of attachment of the chorion to the uterus are, at the equator by 

 the annular placenta, and at each pole of the elongated sac by the 

 subcircular villous patcfi. The umbilical cord was short and rather 

 flattened : it was formed by two arterial and one venous trunks, and 

 by the slender neck of the allantois, with the connecting cellular 

 tissue and the covering of amnios : it measured about fi inches in 



