510 Dr. A. A. Gray. On the Anatomical [June 1, 
downwards and slightly outwards. It is roughly rectangular in shape, and 
its long anterior margin runs close to the tip of the cochlea. This surface is 
covered entirely by bone. The posterior wall runs from the posterior edge of 
the inner wall outwards and backwards. The anterior outer wall runs from 
the anterior edge of the inner surface backwards and outwards to meet the 
posterior wall below the ampulla of the posterior semicircular canal. Lastly 
the inferior anterior wall, which may be termed the floor of the cavity, looks 
downwards, forwards and outwards (in fig. 2 the organ is rotated a little 
clockwise, so that the floor looks downwards, whereas in reality it looks a 
little forwards and outwards as well). The floor is roughly oval or rectangular 
in shape, and is entirely uncovered by bone. It is, however, closed by a thin 
membrane, f7., and looks directly into the tympanum. This corresponds 
anatomically, and perhaps also functionally, to the round window of birds 
and mammals. But this portion of the subject will be referred to later in 
the paper. | 
Pigment is found in the labyrinth of the monitor, scattered in specks over 
the surface of the perilymph recess, including the membrane closing the 
round window. It is also found over the surface of the cochlea, and more 
particularly over the walls of the aqueduct of the perilymph. A few specks 
are found on the wall of the saccule which is adjacent to the cochlea. The 
distribution of pigment, therefore, is very similar in arrangement to that found 
in the lizard and teguixin. It is, perhaps, still more interesting to note that 
the distribution of pigment in the labyrinth of birds in those rare cases in 
which it is found, the ostrich, rhea and tinamou, is similar to that found in 
the teguixin, the lizard and the monitor. In the tortoise and the python it 
is either entirely absent or nearly so, whereas in the gecko it is found equally 
abundant over the whole surface of the labyrinth. 
In addition to the large otolith mass already described as being found in 
the saccule, there is a string of small otoliths in the cochlea which runs 
along the basilar portion of the organ, and on reaching the lagenar portion 
the string of otoliths widens out into a spoon-shaped arrangement along the 
anterior wall. 
Yet another otolith, 0.w.,1s found in the labyrinth of the monitor, and this 
one is of special interest since it forshadows in the reptile the otolith which is 
found in the bird. It is seen in that portion of the utricle which runs 
forwards to the ampulle of the horizontal and superior canals, and lies 
internal to, and behind these ampulle respectively. It is, therefore, in 
exactly the same position in which the otolith or otoliths (for there are some- 
times two) are found in the utricle of the bird. But in yet another respect 
this otolith is similar to those found in the same position in birds. It consists 
