I s c 



tion. Lirni. Gen. 542. Sctireb. 718. Mart. Mill. Dift. v 2. 

 Brown. ProJ. Nov. Holl. v. I. 204. JutT. 30. Lamarck. 

 lUuftr. t. 839. Clafs and order, Polygamsa Manoec'ta, or 

 rather Triandria Digyn'ia. Nat. Ord. Gramina. 



Gen. Ch. Ciil. Glume two-flowered, of two cartilaginous 

 nearly equal valves, fituated tranfverfely ; the outer almofl 

 ovate, tumid, cloven and acute at the top, the upper part 

 of the back flattened, ftriated, bordered; /nwr oblong, boat- 

 like, pointed or awned at the top, furnifhed with a longitu- 

 dinal dorfal membrane below the extremity. Florets fhorter 

 than the calyx, the outer one male, inner hermaphrodite. 

 Qor. (in the hermaphrodite floret) of two thin, membra- 

 nous, pellucid glumes ; the cuter fwelling, cither beardlefs 

 or awned, cloven to the infcrtion of the awn, acute ; czun 

 long, flender, bent, twilled in the lower part ; inner glume 

 lanceolate, acute, it^ margins folded together ; (in the male 

 floret) of two rather firmer, pellucid, fomewhat coloured 

 glumes ; the outer oblong, fwelling, contradied upwards, 

 acute, beardlefs ; inner oblong, obtufe, concave at the back, 

 thinner and acute at the margin : Ne3ary in each of two 

 fmall,- fpatulate, abrupt, notched leaves. Stam. Filaments 

 three, capillary, (hort ; anthers oblong, cloven at each end. 

 Pifl. (in the hermaphrodite floret). Germen oblong ; fl.ylcs 

 two, capillary, ereft, fhorter than the corolla ; ftigmas ob- 

 long, feathery, fpreading, prominent. Peric. npne, except 

 the unchanged calyx and corolla. Seed (in the hermaphro- 

 dite floret) lolitary, oblong, linear, convex at one fide. 



Efl". Ch. Calyx of two vaKcs, two-flowered, placed in 

 pairs, laterally, on a jointed fl:alk ; outer valve flattened. 

 Corolla of two valves, ifhorter than the calyx. Stigmas 

 feathery. One floret male, or neuter. 



Linnaeus' defines two fpecics only, /. niuticum,' Sp. PI. 

 1487, and /. ar[f}attim, ibid. The firft is deltitute of awns,, 

 and is the T'ajadi of Rhecde Hort. Mai. v. r2. 91. t. 49, 

 found in every kind of foil in Malabar, but not of any par- 

 ticular life, except as a grafs in genera'. The root is percn- 

 nia'. 5/c»:j' about a foot high,' round, fmooth,- recd-likej- 

 leafy. Ltaves lanceolate, pointed, broad at the bafe. Spikes 

 terminal, double, fliort, clofe, fliining. /. arijhtum, dillin- 

 guiftred by its awns,- was gathered by Ofbeck in China, and 

 has narrower leaves. 



I. r'ugofmn, S.dif. Ic. i. t. I. Hort. 27.—'' External bar- 

 ren glumes tranfverffly rugofe ; one of the fertile ones, 

 wljether male or female, awned." — Found by Kocnig in the 

 borders of rice fields in the Eail Indies. This is very 

 remarkable for the Ihong wrinkles or furrows of its glumes. 

 Linnxus was inthned to make it a ttew genus by the name 

 of Cieadaria. Mr. Salifbury cultivated it in his Hove at 

 Chapel Allcrton before 1796. 



Mr. Brown in his Prodromus has added fix new fpecies 

 to Ijlbecmum, and alfo ju!Hy refers to this genus the CoUadoa 

 of Cavaniiles, Ic. v. 5. 57. t. 460. 



ISCHEMIA, l-^:u<., in Antiqnttyt anniverfary fports 

 Celebrated at Olympia, in memory of Ifchenus, the grand- 

 fun of Merc\i:y and Hierea ; who, in a time of fa;niiie, de- 

 voted himfelf to be a facrifice for his country, and was 

 honoured with a monument near the Olympian ftadium. 



ISCHIA, in Geography, a volcanic ifland, fituated at the 

 eaftern entrance of the gulf of Naples, about 18 miles iii 

 -^circuit ; the fee of a bifhop, fuffragan of that of Naples, and 

 containing three parilhes, and a cunvent of nuns. The vol- 

 canic I'ubllances of which th'.s ifland is interna ly compofed, 

 prove, beyond the pofSbihty of doubt, fays Spallanzani, 

 •that it owes its origin to fire. The calUe of the city of 

 ^c-hia, as il is called, is built on a rock furrounded by the 

 fea, ;viid a little more than a, quarter of a mile in circuit. 

 t^ ttvo comiJtjnent fubll,auces of this rgck ve lava iuiU 

 6 



rs c 



tufa. About a mile to the weft is a torrent of lava, callecf 

 the " Arfo" or burnt ground, which is the moft recent of- 

 any in the ifland, fince it flowed iu 1302. This lava, thoughr 

 it flowed five centuries ago, is abfolutely fterile ; producing 

 not a fingle blade of grafs, and only afibrding, in' fome places^ 

 a few arid and ufelefs plants of the lichen, or liverwort. On- 

 the furface, and for a little depth, it is light and fpongy, and. 

 eafily crumbles ; but deeper, it becomes dcnfe and harder. 

 This lava is of the hornftone bafe, and has an earthy ground ;; 

 varying in colour from that of iron to a rcddifli-black, and. 

 having incorporated in it very numerous feltfpars. M. Do- 

 loniieu fays, that the eruption of the Arfo, though it con. 

 tinued two years, never produced any pumice, but only 

 black fcorii ; but ispallanzani obferves, that the horniione^ 

 by a violent fire, may be changed into a true pumice. 

 Though this tranfmutation rarely happens, no part of the 

 ifland, however, abounds fo much with pumices as the' 

 Rotaro, a mountain fituated between Cafamicciola and the 

 city of Ifchia. This mountain is of a conical fliape, and com- 

 pofed of tufa, pumices, and enamels. The extent of the-' 

 pumices is more than a mil.?. The Rotaro is the only place 

 in Ifchia which affords enamels. The mountain of St.Nic-> 

 cola, which in earlier times was called Epopeo, and which 

 is in the centre of the ifland, was, as Spallanzani fays, with-' 

 out doubt, the firft that towered above the waves. The c(;n- 

 ftituent fubftances of this mountain are of various kinds. 

 The fulphate of alumine (alum-) was formerly extracted in 

 Ifchia for commercial purpofes ; and the manufafture was 

 principally carried on at Catrico, a place fituated above 

 Laceo, on the higher eminences of the Epopeo. But a' 

 careful obferver has not been able recently to difcover any- 

 remaining veftige of this fubftance. Spallanzani concludes 

 from experiments on different lavas, that this valuable fub- 

 ftance might fti'l be obtained at Ifchia. This ingenious 

 naturalift coafted the ifland and examined various mountains 

 that occupy the lower part of it. He began w-ith the Vico,: 

 which is partly formed of tufa, and partly of two currents 

 of lava, which defcend into the fea. The bafe of both thefe 

 lavas is hornftone, and they abound in feltfpars. He the.l 

 proceeded to Monte Zaro, formed, towards the fea, by a 

 river of lava, extending a mile in length, and nearly two in 

 breadth. The bafe of this lava is hornftune, and it contains 

 mica' and fekfpars. From the termination of Monic Zaro 

 to the commeKcement of Monte Imperatore, is a long and 

 ample traft, almoft entirely tufaceous, fcattered over with' 

 fragments of pumice. The Monte Imperatore prefents dif- 

 ferent fcrcs of lava, the bafe of which is hornftone, inter- 

 mixed with abundance of feltfpars. In many parts of the 

 ifland our author found a ferruginous fand, which not only 

 moves-ihe magnetic needle, but is ftrongly attrafled by liif 

 loadftone. This ifland, our author ap[)reheiid.s, when it was 

 firft produced by conflagrations in ancient, and to us un- 

 known, times, muil liave been of much greater extent than 

 it is at prefent. Time has alfo produced a great alteration 

 in the interior parts of the ifland. From the fummit of 

 F'.popeo, a number of conical eminences may be feen ; hut- 

 their internal craters no longer exift ; nor can be found in 

 Ifchia inconteftible traces of a fingle one, fiuce thofe dvptiis 

 and ample cavities, thole refemblances of theatres and am- 

 phiihoatros, which may be every where obferved, may be 

 equally the efi'ecl of fire or water. The fubllances, cur 

 aulJior conceives, which have furnilhed ah.Tient to the dif- 

 ferent conflagrations of Ifchia, have had their centre in tlx.fe. 

 argillaceous rocks, which, by the above-men; iwied eruption 

 in 1302, fliewed that they were not then exhaufted. See- 

 Spallan-^aifi's Travels in the T%vo Sicilies, &c. vol. 1. 



Along tlu: coafl of llua ifland a lew. pretty viil.-iges are> 

 dilperfud } 



