Many writers have described the spinning of the circular snare, and indeed it is quite easy for any one to watch the operation for himself; but McCook goes into the matter in great detail and figures many interesting variants of its normal form. J. H. Fabre’s delightful _Souvenirs entomologiques_ (Delagrave, Paris) have been issued at intervals for many years past, and mostly deal with insects. In Series 9, however, he has an entertaining chapter on “Les Epeires.” That the “viscid globules” arranged themselves mechanically was first demonstrated by C. V. Boys (_Nature_, xl, 1889, p. 250). The same writer experimented on the sense of hearing in spiders (_Nature_, xxiii, 1880, p. 149). The interesting paper by G. and E. Peckham on the mental powers of spiders is to be found in the _Journal of Morphology_ (Boston U.S.A. i, 1887, p. 403.) The aeronautic habit has engaged the attention of many arachnologists. Blackwall dealt with it in various papers in the _Transactions of the Linnaean Society_ between 1833 and 1841, but the most complete account is to be found in McCook’s original papers which are summarised in his book already cited. With regard to the spinning operations of _Agelena_ the reader may consult a paper by the present writer in the _Annals and Magazine of Natural History_, August, 1891. The habits of the Water Spider were first described by de Lignac in a _Mémoire_ published in 1749. Since that date many writers, notably Wagner and Plateau, have dealt with the subject. The paper by the last named in the _Annales des Sciences naturelles_, 1867, p. 345, is particularly worth reading. E. Peckham deals with “Protective Resemblances in Spiders” in the publication of the _Natural History Society of Wisconsin_ for 1889. The reader interested in the habits of the Wolf-spiders must certainly consult the chapters on “La Lycose de Narbonne” in Series 9 of Fabre’s _Souvenirs entomologiques_. The classical account by the Peckhams, of the love dances of jumping spiders appeared conjointly with the paper by E. Peckham on “Protective Resemblances” cited above. For the habits of _Atypus affinis_ (or _piceus_) the reader is referred to the very complete account given by Enock in the _Transactions of the Entomological Society_ (London, 1885, p. 394) of observations extending through several years. The larger Aviculariidae have been dealt with in various papers by Pocock, and the particulars given with regard to _Dugesiella_ were taken from a paper by Petrunkevitch in the _Zoologischen Jahrbüchern_, xxxi, 1911. In the _Archiv für Naturgeschichte_, i, 1889, Apstein published an admirable piece of research on the structure and function of the spinning glands of spiders. He investigated the glands present in the various families, and the particular arrangement of the spools and spigots on the spinnerets.