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portant to observe, that such a mode of 

 insertion indicates the wholesomeness of 

 the fruit ; we are not aware that there is 

 a single exception to this rule, so that a 

 traveller, who might meet with an un- 

 known fruit, need not scruple to eat it if 

 he find the stamens thus inserted. This 

 character of the insertion of the stamens 

 into the calyx holds good in other classes, 

 as well as in the class Icosandria ; thus, 

 in the genus Ribes, including the goose- 

 berry and currant, which belong to the 

 class Pentandria, the stamens grow out of 

 the calyx, and these fruits are well known 

 to be wholesome, while many of the ber- 

 ries of the same class, whose stamens 

 have not a like insertion, are often very 

 deleterious. 



ICOSA'NDRIAN. Belonging to the class 

 Icosandria ; having twenty or more sta- 

 mens, inserted into the calyx. 



I'DOCRASE. (from idia and Kpaoif, Gr.) 

 A mineral found in lava, and formerly 

 mistaken for the hyacinth ; it is the Ve- 

 suvian of Werner. 



JE'FFERSONITE. A mineral found in New 

 Jersey ; colour olive-green passing into 

 brown. It is named after Mr. Jeffer- 

 son. 



JET. (from Gaga, a river of Asia; jayet, 

 Fr.) The Jayet of Haiiy ; Lignite Jayet 

 of Brongniart ; Pech Kohle of Werner. 

 A mineral substance, found in detached 

 kidney-formed masses in many countries. 

 It is of a firm and very even structure, 

 harder than asphaltum, and susceptible of 

 a good polish. It becomes electrical by 

 rubbing, attracting light bodies, like am- 

 ber. In many respects it resembles can- 

 nel-coal, its colour is full-black, and it 

 does not soil the fingers. It is, however, 

 easily distinguished from cannel-coal, in 

 being specifically lighter than water, which 

 cannel-coal is not, and in possessing elec- 

 trical properties which cannel-coal does 

 not. Some persons have supposed that 

 jet is a true amber, differing only in the 

 mere circumstance of colour. During 

 combustion it emits a bituminous smell. 

 It is never found in strata or continued 

 masses, but always in separate and un- 

 connected heaps. 



It is formed into various trinkets, and 

 is particularly used for making mourning 

 ornaments, such as ear-rings, brooches, 

 bracelets, buttons, &c. 



JEWS- STONE. An extraneous fossil, being 

 the elevated spine of a very large egg- 

 shaped sea-urchin, or echinus. 



I'GNEOUS. (igneus, Lat. ignte, Fr. igneo, 

 It.) Fiery ; containing fire ; produced 

 by the action of fire. In this last sense 

 it is commonly used by geologists when 

 speaking of igneous rocks, or igneous pro- 

 ductions. 



IGNE'SCENT. (ignescens, Lat.) Giving 

 out sparks of fire when struck. 



IGNI'FLUOUS. (ignifluus, Lat.) Flowing 

 with fire. 



IGNI'VOMOUS. (ignivomus, Lat.) That 

 vomits fire. Volcanoes are ignivomous 

 mountains. 



IGUA'NA. A species of lizard, a native of 

 many parts of America and the West In- 

 dies, is rarely met with any where north 

 or south of the tropics. It is from three 

 to five feet long, from the end of the 

 snout to the tip of the tail. It inhabits 

 rocky and woody places, and feeds on in- 

 sects and vegetables. Cuvier states that 

 the iguana subsists upon fruit, grain, and 

 leaves : Bosc, that it lives principally 

 upon insects. It nestles in hollow rocks 

 and trees. The female lays its eggs, 

 which have a thin skin like those of the 

 turtle, and are about the size of those of 

 a pigeon, in the sand. Though not am- 

 phibious, they are said to be able to re- 

 main under water an hour. When they 

 swim, they do not use their feet, but place 

 them close to their body, and guide them- 

 selves with their tails. Captain Belcher 

 found, in the island of Isabella, swarms 

 of iguanas, that appeared omnivorous. 

 This statement proves both Cuvier and 

 Bosc to be correct. The teeth of the 

 iguana are not fitted for comminuting its 

 food, and it is said to swallow it whole. 



IGUA'NODON. An extinctfossil colossal lizard, 

 discovered in the strata of Tilgate Forest by 

 that indefatigable historian of the chalk and 

 Wealden formation, Dr. Mantell, to whose 

 profound and scientific researches the 

 world is indebted for a knowledge of this 

 genus, and whose splendid museum has 

 lately, to the disgrace of the county of 

 Sussex, been removed from Brighton to 

 the British Museum. The following de- 

 scription of this huge animal is almost 

 entirely taken from Dr. Mantell' s Geology 

 of the South-East of England. He ob- 

 serves, " the discovery of the teeth and 

 other remains of a nondescript herbivorous 

 reptile in the strata of Tilgate Forest, a 

 reptile pronounced by Cuvier to be ' en- 

 core plus extraordinaire que tous ceux 

 dont nous avons connoissance,' is one of 

 the most gratifying results of my labours." 

 The remains of one of these immense ani- 

 mals have lately been found in the Kent- 

 ish Rag, near Maidstone. The Kentish 

 rag is a grey arenaceous limestone, be- 

 longing to the Shanklin sands. From the 

 great resemblance in the dentature, as 

 well as in many other extraordinary cha- 

 racteristics, of this immense reptile to 

 that of the iguana, Dr. Mantell determined 

 on naming it the Iguanodon, signifying an 

 animal having teeth like the iguana. In 

 the perfect teeth, and in those which have 



