My dear friend,

I have much pleasure in answering, to the best of my power, the inquiries made by M^r Darwin respecting the impregnation of the Balanus;—had I known that the observation was new, or could possibly possess so much interest as your esteemed correpondent attaches to it, I would certainly have watched the process more critically.² I can only hope on some future occasion to be enabled to supply more precise information, if some other observer should not forestall me.

To take M^r Darwins queries seriatim—

1^st. The Species —Balanus communis?

2^nd. Was the penis inserted into more than one individual? not positive , but I believe it was. It was extended to a length equal to about 3 times that of any single branch of the cirrus, & waved in every direction till it came in contact with the cirrus of a neighbouring balanus, when it was inserted, I believe into more than one. It should be observed that my group is not large, consisting of only 5 full sized animals & a few small ones.

3^rd The insertion did not occupy more than 2 or 3 seconds.

4^th. Not inserted deeply as far as I could judge— at which end of valves was not noticed.

5 & 6. My own impression is decidedly, that the recipient individual was during the time exerting its cirri, with more than usual energy, & gave evidence of the intruder being a welcome guest, but on these points my memory is unfortunately not supported by that of a friend who joined me in noticing the act.

7. The specimens were under water at the time, I have not under other circumstances seen any movement of the cirri.

The particular instance referred to occurred on a fine bright day, about 3 months ago, when the sun was shining full on my glass, and the specimen had been recently taken & was in full vigour. The group still appears healthy, but I have not since observed a repetition of the indulgence of its amatory propensities. Is it a question of season ?

I remain | yours sincerely | R^d. Bishop Spence Bate.