From G. E. Dobson   23 May 1874

Dear Sir

Had I known your address previously I would have sent you immediately on its publication my paper “On Secondary Sexual Characters in Chiroptera”¹ which I now forward for your acceptance, as I know how gladly you receive any fresh facts in Natural History even those apparently at variance with your own opinions.

In connection with some of your remarks in the “Origin of Species” and in “The Descent of Man” (Vol 1. pp. 416, 417) the following notes made by me may interest you:—²

At Allahabad, India, in August 1872, when sitting in my room I saw a Gecko—(Hemidactylus maculatus)³ run swiftly down the wall and seize a rather large very hairy caterpillar. It caught the caterpillar by the middle of its body and struck it violently against the wall so as to force out all the green contents of its intestinal tract and the juices of its body. The gecko then greedily devoured the empty skin.

In this case the armature of irritating spines was evidently not the very least protection to the caterpillar.

Again:— When at Port Blair, Andamans, in the same year, I was struck by the fact that the common tree gecko of the Island, Phelsuma andamanense, has (as Blyth remarked) no claws, but broad disks only, and yet it is essentially a tree-gecko.⁴

In an Island like the Andamans, covered with lofty trees; with even the tops of the hills covered with deep alluvial deposits, without rocks or cliffs, we should surely expect to find a gecko provided with sharp claws for climbing the trees, not with broad disks more suited for running across the perpendicular face of a cliff!—

believe me | dear Sir, | faithfully yours | G. E. Dobson.

Charles Darwin Esq—F.R.S.