1886.] THE INTERVERTEBRAL DISK OF THE AXIS IN MAN. 337 
1], SreRNA MELANAUCHEN, Temm. 
[No. 8. dg. October 9th, 1885. Eye black. 
Common. I have seen this bird pursued by the Noddy Tern, 
just as they themselves are pursued by the Frigate-bird. | 
It would be interesting to know if this species breeds in Diego 
Garcia, because, if so, the locality would be the furthest S.W. as yet 
recorded. 
12. SreRNA FULIGINOSA, Linn. 
[No. 7. 2. October 8th, 1885. Eye black. Very common. 
These birds were laying when I arrived on Sept. 15, and single 
eggs were scattered on the bare ground. The negroes soon took 
all the eggs, and I could not make observations on the breeding. } 
13. Gye1s cANDIDA (Gm.). 
[No. 3. gd. Sept. 25th, 1885. 
Very common, perching in the cocoa-nut trees, and laying a single 
egg in the axils of the leaves, as described by Darwin in his ‘ Journal 
of Researches.’ | 
14. Anous stoxipvus (Linn.). 
[No. 5. 2. October 2nd, 1885. Eye black. 
Common on the island. It constructs a large rough nest of a 
heap of sticks and leaves, in the fork of a tree or bush, and on this 
it lays one egg, upon which it sits. | 
[A bird called by the inhabitants the “Mangeur des Poules” was 
said to visit the island frequently during the N.W. monsoons, but 
I never saw one. Perhaps it may be Tinnunculus punctatus, which 
goes by the same name in Mauritius; but if so it is not easy to see 
why it should visit Diego Garcia only in the N.W. monsoons. 
** Fouquets”’ are abundant on the Ile des Vaches marines at 
Peros Bauhos, and are said to have been seen on the Ile des Oiseaux, 
Diego Garcia, but I never saw one. From the descriptions given me 
they seem to be a species of burrowing Petrel. | 
3. On the Intervertebral Disk between the Odontoid Process 
and the Centrum of the Axis in Man. By J. Buanp 
Surron, F.R.C.S., Lecturer on Comparative Anatomy, 
Middlesex Hospital Medical School. 
[Received May 29, 1886.] 
There are few bones in the human skeleton which can boast a 
more extensive literature than the atlas and axis. Indeed so many 
investigations have been made concerning their nature, and so much 
has been written regarding the morphology of the first two vertebra, 
that most anatomists have abandoned them for more fertile regions 
of the skeleton. Yet, in spite of this attention, a new fact in con- 
nection with the axis has recently been disclosed by Prof. Cunningham 
