Tergum, 96, 143 Terminal plates, 189 Terminology, scientific, 14 Testis, 129 structure of, 133 Thoracic appendages, 164 development of, 217 somites, 150 Thorax, 19, 141 Tissue, 175 Touch, organ of, 113 Transformism, 318 TREVIRANUS, referred to, 4 Tribe, 252 Trichobranchiæ, 263 _Troglocaris_, 337 V. Valves of heart, 73 of stomach, 59 VAN HELMONT, quoted, 45 Variety, 290, 292 Vas deferens, 130 Vent, see Anus _Vertebrata_, 284 eye of, 122, 125 Visual pyramid, 121 rod, 121 Vitelline membrane, 133 Vitellus, 133 Voluntary action, 112 VON DER MARCK, 317 W. WARD, J., referred to, 354 WASSILIEW, quoted, 353 Whirlpool of life, 84 WILL, quoted, 353 WOOD-MASON, quoted, 44 Y. Yelk, 133 Yelk-division, 205 Young of _Astacus_, newly hatched, characters of, 219 Z. Zoæa stage of development, 280 PRINTED BY WILLIAM CLOWES AND SONS, LIMITED, LONDON AND BECCLES. * * * * * * Transcriber’s note: Original spelling and grammar have been generally retained, with some exceptions noted below. Ditto marks have been removed. In the _List of Woodcuts_, the ditto marks have been replaced with em dashes. Footnotes have been relabeled 1–43 and moved from within paragraphs to nearby locations between paragraphs. Illustrations have been moved from within paragraphs to nearby locations between paragraphs. Therefore, the page numbers shown in the List of Woodcuts are sometimes wrong. On page 176 and elsewhere there are phrases such as ‹rarely exceed 1‐700th›, in which the fraction appears to have been printed with a hyphen. In other places, e.g. page 19, there are fractions such as ‹1/110th›, in which the ‹1› was actually printed over a vinculum, over ‹110›, in small text, and this fraction was followed by ‹th› in regular sized text. Herein, both forms have been converted to a form like this: ‹1‐30,000th› (e.g. from page 182), using the Unicode point [u+2010 hyphen]. Page xi. The List of Woodcuts was restructured slightly to form a simple list. Ditto marks and curly brackets were removed. Page 74. The phrase ‹that it to say› was changed to ‹that is to say›. Page 102. The phrase ‹fibre fig. 19, F.)› was changed to ‹fibre (fig. 19, F).›. Pages 228, 292. The word ‹develope› was changed to ‹develop›. Page 282, Fig. 74. Left parenthesis was inserted before ‹The figures A›. Pages 288, 368. The name ‹M’Intosh› appears on page 288, but this name is spelled in the Index on page 368 with what would now be represented by the Unicode character [ʻ U+02BB; MODIFIER LETTER TURNED COMMA] in place of the right single quotation mark. U+02BB is probably correct, but several current browsers don’t support this character. So both instances are spelled herein ‹M^cIntosh›. Page 298. The word ‹kindess› was changed to ‹kindness›. Page 314. The word ‹oocupied› was changed to ‹occupied›.