CYCADACEiE. 703 CYCLICAL FORMS. while the monotypie jMierocyoas belongs to Cuba. In general it is true that Cyc.is and Zamia are the typical cj-cads of the two heniisphort's, wliilo the other genera represent relatively isolated forms which bear the stam[) of local conditions. Fossil Forms. ■ The Cycadacea; arc a group of very great anti(|uity, the genus Cyeas itself ap- pearing to be the oldest of all the" genera of the family-, for it is known from the Carboniferous limestone. This singular type has, since that early time, persisted in modern vegetation, where it stands without any near relatives. The remains of Cycadacea^ attain their greatest de- •velopment in the ilesozoic formations, especially in the Jurassic rocks (Purbcck and WeaUlcn) of England and France, and in the Lower Creta- ceous of the Black Hills of North America, in which latter formation the silicified short cylin- drical stems with their closely crowded, spirally disposed leaf-bases are quite characteristic fos- sils. Also the leaves and fiiictilication of the Cycadaceaj are of frequent occurrence in the Mesozoic beds of the Northern Hemisphere, show- ing that these plants flourished there in that era. In the Tertiary they are rare in Europe, though still occurring in southern Europe. Later their last survivors withdrew mostly to the Southern Hemisphere. With the fossil Cyca- daceee are usually mentioned the MeduHosa;, remains of stems from the Carboniferous and Per- mian rocks, which show many points of resem- blance to the CycadaceiB, while departing from them in some important features. Consult: Von Solms-Laubacli, Fossil Hoiany (O.xford, 1891); Ward, "Description of the Species of Cycadeoi- dea or Fossil Cyeadean Trimks from the Lower Cretaceous Rim of the Black Hills," Proceedings of the United States National Museum, vol, xxi. (Washington, 1S99) ; id., "Description of a New Genus and Twenty New Species of Fossil Cyeadean Trunks from the Jurassic of Wj'oming," in Proceedings of the Washington Academy of Science, vol. i. (Washington, 1900). CYCLADES, sik'la-dez (Lat., from Gk. Ki- Kd5es, Kgllades, (rom KijKos,l'yklos, circle). A portion of the archipelago lying sovitheast of Greece, in the .I'lgean Sea, comprising, according to the old geogi'aphers, the islands of Ceos ( Zea, Kea), Cythnus (Thermia), Seriphus (Serpho), Siphnus (Siphanto), Gyaros, Syros (Syra), Pares, Antiparos, Andros, Tenos, Myconus, Dolos, Rhenea, and Naxos (Map: Gi'cece, F 4). This group, arranged in three series, was su])posed to form a circle with the sacred island of Delos at its centre, and this belief accounts for the name of the group. The modern nomarchy of the Cyelades includes also the islands of Melos, Cimolus, Polycandrus, Sicinus, los (Nio), Amorgos, Santorini (Thera), Anaphi, and a number of smaller islands, some of which were formerly grouped with the Sporades (q.v. ). The total area is 023 square miles. The islands are mountainous, reaching an altitude of over 3000 feet in some instances. Some are of volcanic formation. They ar<> generally scantily watered and sparsely wooded. They produce southern fruits, and large quantities of marble and other valuable building-stones are obtained from them. The population of the nomarchy (province) was 134,747 in 1896. The chief toix-n is Hermopolis (q.v.), on Syra. CYCLAMEN, slk'lii-m(5n (Xeo-Lat., from Gk. KVKd/j.iiios, Icyklaminos, from ki!icXos, kfiklos, circle; referring to its eorolhi). -V gcims of plants uf the natural order Priniulacea'. iiaving a wheel-shaped corolla; with a long rellexcd limb, and llower-stalks twisted spirally downward after flowering. The species are herbaceous per- ennials, not luunerous, and chiefly Alpine in the south of Europe. They have turnip-like, partly subterranean stems, which are very acrid, but, ncertheless are greedily eaten by swine, and the plants are accordingly often designated sow- bread. They are drastic and emnieuagogic. Sev- eral of the species are frequent in our flower- gardens, on account of the beauty and fragrance of their flowers. The most conunou species arc Cyclamen Europaium and Cyclamen- latifolium, the latter being the source from which arc ob- tained many of the forms cultivated as Persian cyclamens. The corolla of Cyclamen latifotium is strongly rellexed, giving the flower a curious appearance, I'^or illustration, see Plate of Gkeemiolse Plants. CYCLE (Lat. cychts, from Gk. k.'kXos, ky- ktos, circle; connected with Skt. cakra, AS. hweOl, Engl, wheel). A term used in chronology to denote an interval of. time in which cerlaiu lihenomcna always recur in the same order. Cycles have chiefly arisen from the iuconnuen- surability of the periods of revolution of the earth and other celestial bodies. Our unit of time is the day of 24 hours, being tile period of revolution of the earth round its axis. But neither the year — the period of the earth round the sun — nor the month — the period of the moou round the earth — can be measured by days, or even by hours, so as not to leave fractions. Cycles have been invented in such a way that after a certain number of revolutions of the body whose period is to be compared with that of the eai'th on her axis, the body shall at last cccupy the same place in the heavens aud calen- dar as it did when the cycle commenced. Of the numerous cycles or periods of this kind that have been invented, the more important are no- ticed under their speciflc names. See l.NUKTiox; -Meton'ic Cycle; Pehiod; Golden Numbek; etc. CYCLICAL FORMS (from cyclic, Lat. cy- clicus, Gk. kiSkXikos, kyktikos, circular, from nixXot, kyklos. circle). In music, forms that consist of a cycle or scries of movements, such as the suite, concerto, sonata, or s3"mphou'. The origin of cyclical forms is to be found in the form of the old overture, which consisted of three parts, the flrst and third being slow, while the middle part was lively. Graduall}' these three parts were extended and detached. In the older compositions the movements were alternately slow and fast. But soon it became customary to begin and end with a fast movement. In the modern s^^nphonv the customarv arrangement is: (1) Fast: (2) slow; (3) fast; (4) fast. But Beethoven's "Sonata." opus 100, and Tsehaikow- sky's "Symphonic Pathi'ticpie." are two famous examples of cyclical com])ositions closing with a plow movement. Originally all the movements of a cyclical composition were written in the same key. The development of the sonata (q.v.) wrought a change in this direction, so that dif- ferent keys (though always related to the funda- mental) were assigned to the different move- ments. The first and last movements, however.
