Prof. R. Owen on the Placenta of the Elephant. 147 



to discover any communication between the true blood-system and 

 the pseudo-vascular ramifications in the mantle or the perivisceral 

 chamber. Injections were thrown into this chamber, but none of 

 the fluid found its way into any part of the lacunary system. The 

 pallial lobes were removed, and the great pallial sinuses distended to 

 their fullest capacity, with exactly the same result ; and it was not 

 until the tissues were ruptured on applying great pressure, that 

 a little of the injected matter was extravasated into the peripheral 

 lacunes. The perivisceral chamber, then, and all its various ramifi- 

 cations, are in no way connected with the true blood-system." 



The nervous system of the articulated Brachiopoda is described at 

 length. Besides the principal suboesophageal ganglion, two minute 

 enlargements are shown to exist upon the anterior part of the oeso- 

 phageal commissure, and two small pyriform ganglia are described 

 in connexion with the under part of the principal ganglion. The 

 peripheral nerves are minutely traced out, and two peduncular 

 nerves, not hitherto known to exist, are described. The author 

 denies the existence of the so-called *' circumpallial " nerves. He has 

 been unable to detect the nervous centres in Lingula, and he is in- 

 clined to regard the cords, described as nerves in that genus by Prof. 

 Owen, as blood- sinuses. 



The author next makes some remarks on the structure of the 

 shell, pointing out that in Terebratulina caput-serpentis there are 

 two distinct layers, an external and an internal ; and he then draws 

 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. 



"On the Placenta of the Elephant." By Professor Richard 

 Owen, F.R.S., &c. 



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 



10* 



