My dear Sir

I have sent you a fragment of an ammonite from the Upper Lias attached to which are some Barnacle-like bodies—¹ In the midst of your other scientific work I would not have troubled you but that they are part of a very interesting study not yet exhausted, some particulars of which I think you may like to know— Some of these little bodies are slightly larger, others still smaller. They do not appear to have the true shell structure of Balanus and in every instance the opercular valves are ancylosed and without a slit— Possibly they are young forms, but, although I have had 40 years experience of these beds I have never found them in a more advanced condition.²

In the Upper Lias there is a wonderfully conservative bed, a few inches thick, containing saurians, fish, Ammonites, &c, &c From this I have a slab 18 inches long with a piece of wood with many Mytilidæ and above them a colony of Pollicipes, but without trace of their peduncles— (I have Pollicipes also in the Rhætic Beds.)³

The same bed contains numerous Ammonites with their Aptychi in position often far back in their outer chambers some of them being almost microscopic. Years ago I wrote a short paper pointing out that there was never more than one Aptychus to an Ammonite, & that being too small for an outer operculum I thought it might perform some office connected with the siphuncular tube—⁴

When Ammonites of 4 to 8 in. in diameter are found in the above bed they usually lie on the surface, or rather the shell has been very gradually denuded, or dissolved away, leaving clear & sharp impressions or moulds of where they lay.— The small ostraea & other shells that were attached to the exterior of the ammonite still lie in the stone below but above these is to be traced the original internal smooth surface of the shell to which they were attached⁵

Curiously enough, the Aptychus, sometimes very perfect still lies in the impression of the outer chamber, and in addition to this portions of the siphuncular tube still remain

But the remarkable fact is this that the tube, or the hollow that represents it appears to have been surrounded by thick membranous layers, in one instance passing round the various whorls for nearly 18 inches in length, the largest part being half as big round as my little finger— Seemingly like the peduncle of cirripedia it was an ovæ-bearing tube, & it had even suggested itself to me, Why might not Aptychus be a parasitic male to the Ammonite?!!⁶

But these Balani? now bother me— A few days ago on examining more closely one of these ammonite impressions I found to my great surprise that the surface was covered with very small globular ovæ, but becoming larger & more disc like towards the outer chamber— Then I found strings of them lying together—like little Nodosarian shells— Next bivalve-looking entomostracan-like bodies presented themselves, sometimes hollow, sometimes pointed at one end, undistinguishable from the horn sheaths containing the antennæ you have referred to in connexion with some of the larvae of the cirripedes⁷

There appear to be several stages of development before they pass into the pyramidal barnacle like forms I have now sent, but I need not now refer to them minutely If these are Cirripedes it will be wonderful to find on a single Ammonite so many points of interest which it took you so much labour & research to determine—⁸

I have these points shewn more or less on about 12 ammonites— If I could brush off from the surface of one specimen, all the ovæ carapaces, &c &c they would about half fill a tumbler!

Some of my Aptychi are in very perfect condition & there is something more to be said of them. Whatever they may be there is no doubt D’Orbingy was mistaken when he figured his specimen, making the cirripedal antennae project through a membrane which united the two valves together⁹

I remain My dear Sir | Yours faithfully | Ch^s. Moore