ACTINIADvE. 



ADANSONIA. 



have n greater tendency to assume different forms than the members 

 of this genus. 



Stout-Armed Animal-Flower (A, cra.tsicomiji}. 



Purple Animal-Flower (A. equina}. 



White Animal-Flower 

 (A. Vianthtu}. 



5. Anllira, Johnstone, includes stich Actinia: as have not the power 

 of retracting their tentacula. Several of the species grow to a large 

 size. 



Example, Anthea Tuediie, Johnstone, ' Brit. Zoophytes,' p. 222, fig. 33. 



6. Aclino/iilja, Blainvillu (Meti-idium, Okeu), species in which the 

 oral dink is divided at the margin into more or less rounded lobes, 

 which bear short simple tentacula. 



Example, .1. ctiamiMU, ' Phil. Trans.,' vol. Ivii., tab. 19, fig. 8. 



7. Capnea, Forbes, of which one species only is known. The disk 

 is round, with several circles of exceedingly short tubercular retractile 

 tentacula, and the body is in part invested with a peculiar epidermis, 

 which is divided at the margin into eight lobes. 



Example, C. tanyuinea. (' Annals of Natural History,' vol. vii., 

 pL 1, fig. 1.) Irish Sea. 



Vapnea sanffuinosa. 

 C. Sea-Anemoniei hating more or few pinnate tentacula. 



8. Actintria, Quoy and Gaimard. Such as have the entire disk 

 covered by very small villose ramified tentacula. 



Example. A. villota, Quoy and Gaimard. (' Voy. Astrolabe, Zooph.,' 

 pi. 49, figs. 1,2.) Tonga islands. 



9. Actinodendrim, Quoy and Gaimard. Species having very long 

 arWescent tentacula disposed in one or two series on the oral disk. 



Example. A. a/< <!>:, ,1. ,/ui. ('Voy. Ast.,' pi. 48, figs. 1,2.) This 

 nimal is more than a foot in height, and secretes a stinging mucus. 



10. Thalaaianthut, Leuckart. One species only is known, the 



T. aster, an inhabitant of the Red Sea, figured in the plates to Riippell's 

 'Voyage.' Its tentacula are numerous, short, and pinnate. It is 

 probably identical with the Epidadia of Ehrenberg. 



11. Jleterodactyla, Ehrenberg. The tentacula are of two sorts, 

 some simple and others pinnate. 



Example, II. ffemprichii. Red Sea, 



12. Meyalictis, Ehrenberg, founded on an animal from the same 

 locality with the last, and characterised by having all the tentacula 

 arborescent, but the internal ones are the larger and more pinnate, and 

 have their extremities hollowed into a sort of socket. 



Example, Megalictis Hemprichii. 



ACTI'NOCAMAX, a division of Belcmnites, proposed by the late Mr. 

 Miller of Bristol, upon the supposition that the species which he 

 ranked in it had no true alveolar cavity or phragmacone. The 

 correctness of this view is doubtful. The species belong to the 

 cretaceous strata. [BEI.EMNITE.] 



ACTINOCARPUS (from iacriv, a ray, and aopinfj, a fruit), a genus 

 of plants belonging to the order Alitmacetf. One of the species of 

 this genus, A. damasonium, is a British plant, though rare. Like the 

 order, it is an aquatic plant, and has cordate, oblong, floating leaves, 

 with white flowers. Another species, A. minor, is sometimes found 

 cultivated in our gardens. 



ACTINO'CERAS, a genus of Fossil Cephalopoda, separated from 

 Orthoceras by Mr. Stokes. The species belong to the PaUeozoic strata. 

 A. Simmii occurs in Ireland. 



ACTINOCRINI'TES, a genus of Crinoidea [EKCRiNiTEs], con- 

 taining many species. It occurs in Silurian and Carboniferous 

 strata. (Miller.) 



ACTI'NOLITE, a crystallised mineral of a green colour, a variety 

 of hornblende, found in primary stratified rocks, and occasionally in 

 trap-rocks. The name is derived from aicrty, a ray of light, and 

 Ai'floj, a stone, from the crystals being arranged in the form of rays. 

 It occurs in masses or asbestiform. 



ACU'LEUS, or Prickle, in Botany, is a hard, conical, often curved 

 expansion of the bark of some plants, such as the rose, and is intended 

 either for their defence against enemies, or to enable them to hook 

 themselves upon their neighbours, so as to gain a more free access to 

 light and air, or for other purposes unknown to vis. The prickle is 

 composed entirely of cellular tissue, which is at first soft and flexible, 

 and only acquires its hardness and rigidity when old. In some respects 

 it may be compared to a hair, from which it chiefly differs in its large 

 size and greater permanence. Care must be taken by the young 

 botanist not to confound the prickle with the spine or thorn, which 

 is of a totally different nature. [SPINE.] They may be distinguished 

 by the prickle breaking readily from the bark, and leaving a clean scar 

 behind ; while the spine cannot be torn off without rending through 

 the bark into the wood itself. Leaves are often metamorphosed into 

 spines, but never into aculei. 



ADAMANTINE SPAR, a simple mineral, more commonly deno- 

 minated Corundum by mineralogists, the name given to it in India, 

 from which country it was first brought to Europe. The first 

 specimens of it were sent by Dr. Anderson, of Madras, to Mr. 

 Berry, a lapidary in Edinburgh, as the substance used in India to 

 polish masses of crystal and all other precious stones, except the 

 diamond. It was examined by Dr. Black, who ascertained its peculiar 

 nature, and from its great hardness he called it Adamantine Spar. 

 With the exception of the diamond, it is the hardest substance 

 known. It contains about 90 per cent, of alumine, a little iron, and 

 a little silica, is usually of a pale grey or greenish colour, but is also 

 found of various tints of red and brown. It is usually met with in 

 rough ill-defined crystals, in granite, and sometimes in primary 

 limestone, and is found in China, many parts of India, and occa- 

 sionally in different parts of Europe. Emery, the well-known 

 substance used in the cutting and polishing of glass, in polishing 

 steel, making razor-straps, and similar purposes in the arts, is a 

 granular variety of Corundum, usually very much mixed with iron 

 ore. It is chiefly imported from the Isle of Naxos, in the Grecian 

 Archipelago, but is also found in Saxony. The Sapphire is a 

 remarkable instance how the mysterious chemistry of nature in the 

 mineral kingdom produces from the same elements substances the 

 most different in external form ; this beautiful precious stone yielded 

 by the analysis of Chenevix 94 per cent, of alumiue ; and Tennant 

 found in emery, when freed from its admixture of iron, 92 per cent. 

 of the same earth. The sapphire is, after the diamond, the must 

 valuable of gems; it is ufmally dark blue, but also occasionally colour- 

 less, and the precious stones called by lapidaries Oriental Ruby, Oriental 

 Topaz, Oriental Amethyst, and Oriental Emerald, are red, yellow, violet, 

 and gien Sapphires, distinguishable from the other gems of the same 

 name which have not the prefix Oriental, by their greatly superior 

 hardness and greater specific gravity. Sapphires are found in gravel 

 and sand in the island of Ceylon and in Pegu, but they have never 

 been seen in a matrix. They are also occasionally found in gravel in 

 different parts of Europe, and they have been met with of a clear 

 blue colour and crystallised, in the lava of Nieder Mendig, near 

 Andernach on the Rhine. 



ADANSONIA, so called in honour of Michael Adanson, the French 

 naturalist, is an extraordinary tree found in Africa within the tropics, 

 particularly in Senegal, where it is called Baobab. 



