Shells broken by Dytiscus, 33; Mr. Kew on dispersal of, 130. Shore Crab, 136. Shore-hopper, 151. Shrimp, 132. _Sialis lutarius_, larva of, 177; W. Evans on, 177; anatomy of, 180; pupa of, 182. Sicarius, 158. Simmermacher on Hydrophilus, 53. Sirex, 82. Sowerby, G. B., on Dytiscus, 34. Sphaerium, 130. Sphaeroma, 155. Spiders, general description of, 96; Trap-door, 97; Hunting, 98; Garden, 98; Jumping, 105; Diving, 108. Stebbing, Rev. T. R. R., on etymology of Dytiscus, 33 _n._; on Malacostraca, 128; on meaning of _chelate_ and _sub-chelate_, 132 _n._; on Amphipods, 141. Stewart, Professor, incident of, 20. Stilopyga, 63. Swammerdam on Blatta, 74; on Nepa, 89; on Water Mites, 114; on Woodlice, 156; on Dytiscus larva, 158, 159. Tailed Wasp, 82. _Talitrus locusta_, 151; Bate and Westwood on, 151; Mr. Robertson on, 152. Tanypus, larva of, 176. Tegetmeier, Mr. W. B., on destruction of shells, 34. Thomson, J. A., on Spiders, 100. Trap-door Spider, 97. Vertebrates, 28. Wart-eater, 81. Water Beetle, Margined, 31; the Great, 49. Water Boatman, 93. Water Bugs, 86. Water-devil, 157. Water Mites, 113; Swammerdam on, 114; De Geer on, 116; Dugès on, 117; Mainland on, 118. Water Scorpion, 86. Water-tiger, 157. Westwood on Locusta, 81. White, Gilbert, on Blatta, 64. Wing-cases, 41. Wireworm, 126. Wood, Rev. J. G., on lens stand, 15. Woodlice, 155; Swammerdam on, 156. Worms, 29. Wright, Mr. L., on microscopes, 16. Zeiss, lenses of, 15. THE END. FOOTNOTES: [1] Darwin, _Descent of Man_ (2nd ed.), p. 159, note 23. [2] The power of magnification of a lens is the ratio of its focal distance to 10 inches. Thus a lens of 1 inch focus (or focal distance) magnifies 10 times (written × 10, or ten diameters); one of ½ in. focal distance, 20 times, and so on. [3] _A Popular Handbook to the Microscope_, p. 39. [4] _Journal of the Quekett Microscopical Club_, v. 148. [5] _Ponds and Rock Pools_, p. 17. [6] _Bulletin of the Illinois State Laboratory of Natural History_, iv. 158. [7] ‘Dytiscus’ is written of set purpose. It is not, as some people tell us, a miswriting for Dyticus; but a properly formed diminutive, from the Greek _dutēs_ = a diver; like _paidiskos_ = a little boy. Linnaeus consistently calls the genus Dytiscus from 1735 onwards. Dyticus only dates from Geoffroy’s _Histoire Abrégée des Insectes_, first published anonymously in 1762. On this question of nomenclature I am glad to have the support of the Rev. T. R. R. Stebbing, F.R.S., who, in answer to my inquiries, kindly wrote, ‘Darwin uses “Dytiscus” in the _Origin of Species_, and I should decidedly recommend its being upheld.’