The date of Louis Pfeiffer's description of this species is inconsistently cited in scholarly works as well as on the Internet. A search of the latter resource for this species using "kochi Pfeiffer" produced 49 hits for 1821 (when he was a teenager), 46 for 1845, and 0 for 1846. Refining the search to "kochi L. Pfeiffer" elicited 7, 3, and 6 respectively.

    The original description of Helix kochi can be found at <http://www.biodiversitylibrary.org/item/46217#page/341/mode/1up> (bottom of p. 127). I became suspicious of the date of publication when I saw, on the last page (143) of this issue  (<http://www.biodiversitylibrary.org/item/46217#page/357/mode/1up>), mention of the cancellation December 23 [1845] meeting of the Zoological Society. It seemed a bit unlikely that the magazine got into print over the holidays.

    I finally found evidence of the basis for this anachronism (Waterhouse, 1893: 438, bottom L column: <http://www.biodiversitylibrary.org/item/97156#page/550/mode/1up>): February, 1846 was the publication date for Helix kochi L. Pfeiffer in the PZSL for 1845: <http://www.biodiversitylibrary.org/item/46217#page/209/mode/1up>.

     Note this erroneous "antedating" was epidemic in the mid-nineteenth century, e.g., <http://www.jaxshells.org/0050a.htm> and  <http://www.jaxshells.org/10088.htm>. In the case of the topical species, even the great master, H.A. Pilsbry (1848: 591), was snookered by it:
<http://babel.hathitrust.org/cgi/pt?u=1&num=591&seq=95&view=image&size=100&id=uc1.31822000620260> no doubt entraining the Internet proponents of 1845 as the correct date.

    How 1821 entered the mix is presently unexplained, but there must have been some mindless copy-cating, an Internet phenomenon we've witnessed on many other occasions.

    Having learned my lesson well, I even felt compelled to verify the publication date of the collation by Waterhouse in a later issue of PZSL (August 1, 1893); see <http://www.biodiversitylibrary.org/item/111041#page/985/mode/1up>, <http://www.biodiversitylibrary.org/item/111041#page/986/mode/1up>, and bibliography below!

Literature cited:

Duncan, F.M., 1937. On the dates of publication of the Society's "Proceedings" 1859-1926. With an appendix containing the dates of publication of "Proceedings" 1830-1858, compiled by the late F.H. Waterhouse, and of the "Transactions" 1833-1869, by the late Henry Peavot, originally published in the P. Z. S. 1893, 1913. Proceedings of the Zoological Society of London 107: 71-84. [not seen]

Pfeiffer, L.,1846. Descriptions of thirty-six new species of Helix, belonging to the collection of H. Cuming, Esq. Proceedings of the Zoological Society of London, for 1845 13(153): 126-133. February. <http://www.biodiversitylibrary.org/item/46217#page/340/mode/1up>.

Pilsbry, H.A., 1948. Land Mollusca of North America north of Mexico vol. II part 2. Academy of Natural Sciences, Philadelphia. xlvii + 521-1113. 19 Mar.
<http://babel.hathitrust.org/cgi/pt?view=image;size=100;id=uc1.31822000620260;page=root;seq=7;num=i >.

Waterhouse, F.H., 1893. List of the Dates of Delivery of the Sheets of the 'Proceedings' of the Zoological Society of London, from the commencement in 1830 to 1859 inclusive. In: May 2, 1893. Sir W.H. Flower, K.C.B., LL.D., F.R.S., President, in the Chair. Proceedings of the Zoological Society of London, for 1893(2): 436-440. 1 August.
<http://www.biodiversitylibrary.org/item/97156#page/544/mode/1up>.