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 inter alia) 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 variety.¹

I will now explain my operations 1^st. those of Huafo & Mocha I have described as T. Chilensis 2^d that of Port Desire, together with the Navedad (T. carinifera) and several specimens without locality, but numb^d. 632 I have described as T. Patagonica. 3^d the S^t. Julian must be regarded as neither more nor less than T. ambulacrum 4^th I w^d. strike out from the Navedad series the one resembling T. carinifera 5^th Also the T. Ambulacrum with somewhat variable external characters from the Port desire list. 6^th Of the additional specimens one (numbered 632) is already disposed of; the two others are such mere casts or fragments that they cannot be brought into the account. 7^th 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. Patagonica, the rest are probably Ambulacrum, but are very indistinct.

The specimens 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 17^th Jan^y /46—

N.B. Too late for post.