Page 345. The graphic chart, _Successive Forms of the Astacomorphous Type_, is poorly represented in our text edition, due to the inherent limitations of plain text. An image is used in the html edition. Page 363. The original INDEX was structured loosely as a nested list. In the simple text edition, this structure has been reproduced as well as possible. In the html/epub/mobi editions, an html nested list structure has been imposed. Html list code is more rigidly semantic than the original printed index, so some corrections had to be applied, and ambiguities were necessarily clarified. A few mistakes are possible during such a process.