My dear Darwin.

Having at length reached home I return your M.S. which appears to me to convey a perfectly correct account of the defensive organ of the Polyzoa—¹ I have made one or two verbal alterations and do not at all like the use of the word Corallines for these creatures—²

I have looked into Smitts papers but have been unable to find anything bearing more directly on the point of homology than the following “—Organa illa secundaria coloniæ (setæ—ooæcia—avicularia et vibracularia soboles) quae gemmificatione secundaria sæpissime supra zooæcia oriuntur, Quamvis etiam zooæciorum modo gemmificatione primaria oriri possint. Immo etiam modificationes ejusdem typi atque zooæciorum videri possint” and in another place he describes the vibracularia & Avicularia) as arising by gemmation & fission, & as altogether corresponding with the polype-cells in other species—”— But this is perhaps sufficient to indicate his assent to their homologous nature.³

In order to show you what I look upon as transitions between vibracula & avicularia I enclose One or two figures—one of a species collected by yourself in the Falkland Islands. in which this quasi transition appears to be clearly manifested.⁴

Hoping I have not inconvenienced you by keeping the paper so long

I am | Yours very truly | Geo Busk