Published June 10, 1873 according to Marshall B. A. (1991)
The Nautilus, 105 (3): 104-115. This is a reprint published in advance of
Memorie della Reale Accademia di Torino, (2) 27: 33-294 (November, 1873) with identical contents but distinct pagination. The date "1872" on the title page is in error and contradicts the contents, with some cited references for 1873