ON THE ANATOMY OF A FOUR-WINGED CHICK. 315 
On the Anatomy of a Four-winged Chick. 
By Rosert Broom, M.B., C.M., B.Sc., Taralga, New South Wales. 
[Read 30th April, 1895.] 
A sHoRT time ago I obtained, through the kindness of Mr. Beatty, 
Shellharbour, a newly-hatched abnormal chick, and, as it shows 
very clearly the nature of the supernumerary limbs, f think it 
worthy of description. The head is normal, and the body appears 
about natural size, but is possessed of four wings, four legs, and 
two tails. When examined on the underside, there is found a 
single umbilicus near the centre of the body, and on the same 
level, directly opposite each other, are the two tails. The four 
legs are normally placed relatively to the two tails, so that two 
knees are situated near the root of the neck, and the other two at 
the extreme anticephalad end. On the dorsal aspect, the spinal 
axis appears to cleave at the root of the neck, and the two branches, 
after running parallel for some distance, are seen to diverge to the 
two lateral tails. Near the root of the neck arise two wings, 
which appear normally placed relatively to the head. At the 
anticephalad end are another pair of wings, situated closely to- 
gether in the cleft between the two diverging axes, with the 
elbows pointing outwards and the phalanges away from the head. 
A little dissection reveals the exact nature of the abnormality. 
The vertebral axis becomes cleft in the upper cervical region, so 
that, although there is but one head, there are two complete spinal 
columns. For convenience, I will refer to the vertebral column 
to the right of the mesial line of the head as “ Spine R.,” that to 
the left as “Spine L.” Though the spines run close together and 
almost parallel in the thoracic region, yet all the costal elements of 
both sets of dorsal vertebre are developed. The right ribs of 
“Spine R.” are approximately normal in shape and development, 
and, passing to the front, are joined to a normally developed 
_ sternum, which is on the left supported by the equally well- 
developed left ribs of “Spine L.” It will thus be seen that there 
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