S T I 



L418] 



S T I 



to its greatly expanded conditions 

 in the tortoise and the bird, which 

 severally exhibit the most opposite 

 proportions of these animals." 

 STI'GMA. (a^ifia, Gr. stigma, Lat.) 

 In botany, the apex of the pistil ; 

 the stigma is variously formed, 

 being either a fine point, a round 

 head, or lobed; generally downy, 

 often hollow and gaping, and more 

 or less moist. Sometimes, though 

 there is only one style, there are 

 two or more stigmas ; when there 

 is no style, the stigma is sessile on 

 the ovarium. 



STIGMA'BIA. A family of extinct fossil 

 plants of the coal formations. The 

 stigmaria was an aquatic plant, 

 inhabiting swamps or lakes, and, 

 as regards its external structure, 

 resembled the euphorbiaceaB. Frag- 

 ments of stigmariaB occur abundantly 

 in the coal shales. It appears to 

 have been dicotyledonous. 



"Authors are by no means 

 agreed," says Sir H. De la Beche, 

 " as to what families certain genera 

 of fossil plants should be referred. 

 Thus M. Ad. Brongniart refers the 

 genus Stigmaria, very common in 

 the coal measures, to the family of 

 Lycopodiacea3 ; while Lindley and 

 Hutton consider that, if any exist- 

 ing analogy must be found, it is 

 with greater probability of accuracy 

 referrible to the Euphorliacece or 

 Cacte, most probably to the for- 

 mer; a difference of considerable 

 importance, as upon it depends 

 whether the genus in question 

 belongs to the class cellurares, or to 

 the class vasculares. This difference 

 of opinion arises, no doubt, from 

 the obscurity of the subject, fossil 

 botany being beset with very great 

 difficulties; difficulties far beyond 

 those which attend the study of 

 fossil zoology, though the latter are 

 by no means either small or rare." 

 STI'GMATA. Spiracles from which the 



tracheaa of insects commence. 

 STI'LBITE. (from <rnX/3w, to shine, 



Gr.) Prom the degree of lustre 

 which it possesses. The radiated 

 zeolite of Jameson ; strahl- zeolite of 

 Werner ; prismatoidischer kuphon- 

 spath of Hohs. Stilbite is of a 

 white colour generally, sometimes 

 pure, at others shaded with grey, 

 yellow, or red. It occurs both 

 crystallized and massive. It is 

 splendent externally ; internally 

 shining and pearly. Translucent, 

 and sometimes transparent. Specific 

 gravity 2-2. Hardness 3-5 to 4'0. 

 It does not scratch glass. It con- 

 sists of silica 52*5, alumine 17*5, 

 lime 11-5, water 18'5. It occurs 

 in secondary trap rocks, in Scotland, 

 Norway, and in the Faroe islands. 



STINK STONE. (Called also Swine- 

 stone.) The name given to a va- 

 riety of limestone, from the fetid 

 odour which it gives out on friction ; 

 a smell resembling rotten eggs. It 

 is the chaux carbonate e fetide of 

 Haiiy; the stinkstein of Werner. 

 It occurs in masses, either compact, 

 or having a granular or foliated 

 structure, frequently forming large 

 beds, or even whole mountains. 



STIPE, (stipes, Lat.) In botany, the 

 stem or base of a frond ; a species 

 of stem passing into a leaf, or not 

 distinct from the leaf; the name 

 given to the stem of palm trees ; it 

 differs essentially in form, struc- 

 ture, and mode of growth, from 

 the trunk, increasing in length 

 only, and not in thickness. The 

 stem of a fungus is also called a 

 stipe, as is the thread, or slender 

 stalk, which supports the down, 

 and conncts it with the seed. 



STI'PULA. | (from stipula, Lat.) In 



STI'PULE. j botany, a membranous 

 leafy appendage, placed at that part 

 of the stem whence the leaf or 

 footstalk arises. Stipules vary Jin 

 number, being solitary or in pairs ; 

 in situation, being either external 

 with regard to the leaf or footstalk, 

 or internal, the internal sometimes 

 embracing the stem in an undivided 



