areolæ or corpuscula in the albumen of all the European genera of Coniferæ, 574-5
Scitamineæ, structure of flower in, 49; formation of albumen in, 452
Scoresby, Captain William, catalogue of plants collected in Spitzbergen by, 179
Scrophularinæ, observations on the species found in the vicinity of the Congo, 135; in the collection from Central Africa, 296
Seeds never produced entirely naked, 359
Seeds and fruits, on some remarkable deviations from the usual structure of, 357
Seguieria forms with Petiveria, a subdivision of Phytolaceæ, 140
Sempervivum tectorum, monstrosities in, illustrating the origin of ovula, 563
Sesameæ, one species in the collection from central Africa, 295
Smeathman, Henry, number of species of plants collected by him at Sierra Leone, 101
Smeathmannia referred to Passifloreæ, its character and affinities, 386-7 note, 121, 381
Smith, Christian, plants collected by him in the vicinity of the Congo, 99, 173
Smith, Thomas, his observations on the general existence of the foramen in the membranes of the ovulum, 411
Sowerby, G. B., jun., his drawings of Triplosporite, 585
Sphenoclea Zeylanica, identity of specimens from Congo, and various parts of Africa, Asia, and America, 170, 171
Spiral tubes produced on the surface of the aerial roots of Orchideæ, 548; on the inner surface of the corolla of Ceropegia, 549; in the wool enclosing the spines of Mammillaria and Melocactus, ibid.; in the coma of the seed of an Apocyneous plant from Brazil, ibid.
Spiral vessels, stratum of, beneath the outer coat of the seed of Casuarina, 46
Spiral fibrous, tubes containing and emitting mucus in Blennodia and Matthiola, 316
Spiral vessels in the bulb-like seeds of certain Liliaceous plants, 364; do not appear to exist in any part of Rafflesia Arnoldi, 377; shown to exist in various parts, 412; exist also in Hydnora, Cytinus, Balanophora, Cynomorium and Helosis, ibid.
Spitzbergen, catalogue of plants collected in, by Captain Scoresby, 179
Stackhouseæ, characters of the order and observations on its distribution in Terra Australis, 27
Stelis, spirally striated cells in, 515
Sterculia, several species produce seeds which become naked by the early regular dehiscence of the ovarium, 363
Sterculiaceæ, compared with Rafflesia, 388-9
Stigma, on the relative position of the divisions of stigma and parietal placentæ in the compound ovarium of plants, 553—563; origin and type of, 558; necessarily consisting of two parts, not terminal but lateral, 558, 560; whence inferred, ibid.; the two stigmata of each carpel generally confluent, 559; exceptions in Parnassia, Cruciferæ, and Papaveraceæ, where the stigmata as well as the placentæ of the adjoining carpels are confluent, ibid.; how proved, ibid.; in Irideæ, also, where the stigmata alternate with the cells of the compound trilocular ovarium, ibid. characters derived from modifications of stigmata of less value, 560; composition of, in Orchideæ, 501-4; functions of its different lobes in, 503; relative position of stamina and stigmata, 504
Sturt, Captain Charles, plants found in his expedition into the southern interior of Australia, 313, 337; in his expeditious to the Darling, Murrumbidgee and Murray, 338
Style, a mere attenuation of the whole body of the ovarium, 558
Stylideæ, observations on the order and its distribution in Terra Aus-
