1

My dear Sir

You will probably have expected this sooner, the points to be settled were however difficult - After the most careful examination of all the specimens the result will appear in the separation of two sorts from T. ambulacrum this I have done, not because I am myself fully satisfied of its propriety, but because I found characters which would be considered satisfactory (as distinguishing characters) by some (D'Orbigny interalia) characters which some would regard as specific, others as only variations - however my opinion is that wherever a combination of characters distinguishing one subject from another exist, they should always be noticed, whether they be considered as the characters of a species or only of a

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variety.

I will now explain my operations

1st      those of Huafo & Mocha I have described as T. Chilensis

2d      that of Port Desire, together with the Navedad (T. carinifera) and several specimens.

          without locality, but numbd. 632 [in Darwin's hand:] I have described as T. Patagonia.

3d      The St. Julian must be regarded as neither more nor less than T. ambulacrum.

4th     I wd strike out from the Navedad series the one resembling T. carinifera       

5th     Also the T. ambulacrum with somewhat variable external characters from the Port

          Desire list.

6th     Of the additional specimens one (numbered 632) is already disposed of; the two

          others are sure mere casts or fragments that they cannot be brought into the

          account.

7th     I must now add with respect to the fragments from Navedad formerly said to

          resemble carinifera, but which I now recommend you to strike out, that, one fragment

          also belongs to T. Patagonia, the rest are probably ambulacrum, but are very

          indistinct.

The specimen shall be packed up on Monday or Tuesday and sent to the Geol. Society for you.

I am My Dear Sir

Your very obliged,

G B Sowerby

17th Jany / 46-

NB. Too late for post.