THIS is an excellent work, devoted to the orchids of extra-tropical South Africa, and arranged on the lines of the “Refugium Botanicum” of Mr. Wilson Saunders. The first part includes fifty plates, containing figures and dissections (partly coloured) of fifty-one species. The text comprises descriptions in Latin and English, references to original descriptions, synonymy, geographical distribution, with critical and explanatory notes. The author's many years of careful study of South African orchids, as well as his previous writings on the subject, are sufficient guarantee of the quality of the work; and as regards the plates, a decided improvement is noticeable, both in the drawings and lithography, as compared with his previous “Orchids of the Cape Peninsula” (reviewed in NATURE, vol. xxxix. p. 222). The work will be of great use to the systematic botanist, for, as Mr. Bolus has well pointed out, few orders of plants stand more in need of illustration from living specimens than orchids, because of the high degree of specialisation of many of the parts, some of which are very fleshy, and seldom recover their shape after soaking or boiling. Nine new species are described in the present part, Angraecum caffrum, A. Maudae, Habenaria Galpini, Satyrium Guthriei, S. ocellatum, Pachites Bodkini, Disa sabulosa, D. conferta, and Brown leea Galpini. There are strong grounds, however, for suspecting that Satyrium Guthriei is not a true species, but a natural hybrid. It was described from a single living specimen found growing with S. candidum, Lindl., in burnt-off places on the Cape Flats, Tokai, near Cape Town, by Mr. F. Guthrie. Mr. Bolus remarks that the column “resembles in some degree that of Satyrium bicallosum, Thunb., while both are in this respect very different from that of any other Satyrium known. In every other character this differs greatly from S. bicallosum, and I very much doubt if it is a natural hybrid.” This remark shows that Mr. Bolus had suspicions about the matter. It is a remarkable fact, however, that in every character in which S. Guthriei differs from S. bicallosum it approaches S. candidum; in fact, with the exception of the column, it bears a much closer resemblance to the last-named species, and as the organs generally are intermediate in character between those of the two species, there seems little doubt that it is a natural hybrid between them. Many such organisms are now known, and as both the species grow in the district, there is nothing improbable about the matter. Icones Orchidearum Austro-Africanarum Extra-tropicarum; or Figures, with Descriptions of extra-tropical South African Orchids. By Harry Bolus Vol. i. Part 1. (London: William Wesley and Son.)