My dear Sir

I know well that I have no excuse for troubling you, but you once most kindly said you would compare any specimens with Spenglers;¹ if you would now do so, it would be a very great favour.

1^st. Is the Lepas mitra of Spengler a Conia or Tetraclita of Schumacher;² that is have the walls of the shell many rows of tubes, like the two valves sent? Is L. mitra white? is it narrowly ribbed like these two valves? If L. mitra be a Tetraclita, then I believe these valves belong to this species.

2^d. I send two species of Balani, large & small, adhering together:— are either of these the Lepas purpurea of Spengler or its variety, or again are either Lepas balanoides var b lineis rubris.³ The difference between the two specimens sent, is great: if you will break the larger you will find the walls are not tubular only internally ribbed, & the edges of the radii (= areæ depressæ = areæ interjectæ) are quite smooth; and the margin, as seen without disarticulation, rounded.— In the smaller specimens the walls are tubular & the edges of the radii crenated or toothed. In the larger specimen the anterior valves of the operculum are longitudinally striated or furrowed. Without one specimen of Spenglers be disarticulated, it will be hardly possible to identify the species. My specimens may be destroyed.

In my letter thanking you for your most kind present of Xenobalanus⁴ I asked you kindly to inform me where the name is published, & the habitat of the species.—

My volume on the Pedunculated Cirripedes will soon be distributed by the Ray Society: I have given, some curious facts, I think, on the sexes of some Cirripedes.—

With the highest respect | I remain Dear Sir | Yours sincerely | C. Darwin To | Professor Steenstrup | The Museum | Copenhagen.

It is quite possible that the specimens sent may not belong to either L. purpurea or balanoides var b. but I think they must.