My Dear Sir,

I believe I have made a discovery which will greatly interest you   It is no less than the method by which tails are lost and I have found evidence of the process in man which I think will prove as weighty as “Darwin’s ears” is in another direction.² It is too long a matter for me to go into now but let me merely say that the process is the occurrence of spina bifida and the remnant in man of the process consists of depression of the skin over the point of the coccyx & its union (by fascial adhesion) to the post. surface of the tip bone. I have been engaged all morning in making casts of the depressions in a family of children who have it marked in all & very marked in one. The mother has it. The very marked one I try to give you an idea of in the diagram below. The depression is tubular & quite half an inch deep³

Yours truly | Lawson Tait

child aged 6 $\frac{1}{2}$

I think it quite on a par with the pharyngeal fistula which indicates the lost bronchial opening & the labial furrow which shows the lost hare-lip.⁴

LT

I’ll send you a cast⁵