Dear Sir,

Up to now I have shamefully neglected to send you my sincerest thanks for the kind and encouraging letter with which you replied to the impertinent appeal I made upon you to criticise an unripe hypothesis of mine.¹ According to your advice and my own conviction I have provisionally put it back in its corner/drawer to see whether in time facts may be gleaned either supporting or invalidating it.

Since then I sent you a short account of the results I arrived at, regarding the affinities of the different genera of Nemerteans²

The anatomy of this group discloses other highly interesting facts, the principal of which I suppose to be the discovery of a central nervous system situated entirely above the intestine.³ Central in its character because down to the furthermost extremity of the tail a continuous and equal sheath of nerve cells accompanies a central bundle of fibres in the so called lateral nerves, which latter merge into one another in the tail by a commissure situated above the anus.

The internal segmentation of these animals as well as some other points in their anatomy leads me to the conclusion that here we have a group much more nearly related to the primitive intermediate forms between invertebrate and vertebrate than are either the more modern ancestors the annelids (whose “Bauch Mark” offers so strong an objection but can in its turn be easily derived from such forms of Nemerteans as is f. ex. Drepanophorus) or the original candidates for this honour: the ascidians.⁴

Within a few weeks I hope to prezent to our royal Society paper on this subject which you will permit me to send you.⁵