507 
— An Investigation on the Anatomical Structure and Relationships 
of the Labyrinth in the Reptile, the Bird, and the Mammal. 
By ALBERT A. Gray, M.D., F.R.S.E. 
{Communicated by John G. McKendrick, M.D., F.R.S. Received June 1, 1908.) 
[PuatEs 19 anv 20.] 
_ The object of this paper is to give a description of the labyrinth of certain 
animals, illustrating the organ when it is viewed as a whole in examples 
chosen from the reptiles, birds and mammals. 
The method of preparation employed was that devised by the writer and 
described in the “ Labyrinth of Animals,” vol. 1, p. 8. By the use of this 
method new facts have been brought to light, and these enable us to 
elucidate certain relationships in the anatomical structures ‘which have 
hitherto been obscure and which anatomists are not agreed upon. The 
structures referred to are, the aqueduct of the perilymph, the perilymph 
recess and the round window. A special portion of the paper, therefore, 
has been directed to this aspect of the subject. 
Before proceeding to describe the organs mentioned, the writer would like 
to thank very cordially those who have assisted him in obtaining material. 
Since some of the animals are rare and difficult to obtain, it will naturally be 
understood that the writer is very grateful to those who have given them 
to him for preparation, and he is glad to have this opportunity of thanking 
the Zoological Society of London, the Royal College of Surgeons of London, 
and the Hon. N. Charles Rothschild. 
The Membranous Labyrinth of the Momtor (Varanus salvator). 
(Plate 19, figs. 1, 2, and 3.) 
In extracting the labyrinth of this reptile it was found possible to make 
4 more complete preparation of the organ than was done in any of the 
reptiles examined hitherto. This has brought into light some interesting 
facts which help to elucidate considerably the relationship of the reptilian to 
the avian and mammalian labyrinths. © 
The organ measures 8 mm. in its greatest length from the junction of the 
superior and posterior canals to the tip of the cochlea. The cochlea measures 
35 mm.in length from the oval window to the tip, and the tube of the 
cochlea measured at its base is 1°75 mm. in diameter. The reason why this 
