1089 



TRAPA. 



TREMELLINI. 



1090 



aspect of the rocks now called Trap, in successive terraces on hill sides, 

 is such as often to justify the use of the word. In modern works on 

 topographical geology a very great proportion of the ancient rocks of 

 fusion are familiarly called Trap, not because they have any certain 

 mineral composition, but because, whether granitic, selenitic, porphy- 

 ritic, or hornblendic, they appear under particular relations of position 

 or geological age. In this sense the term is purely geological, and we 

 have as distinctive designations Eruptive Trap, Contemporaneous 

 Trap, Overlying Trap, Interposed Trap, &c. By other writers the 

 term is restricted so as to leave out such massive and generally deep- 

 seated rocks as granite, or even contracted to the hornblendic and 

 felspatho-hornblendic rocks, which appear as dykes, interposed beds, 

 and overlying masses. It thus appears to be a collective term more 

 convenient than precise. In a geological sense it may be replaced by 

 descriptive words, such as Irruptive, Interposed, Overlying, &c., and 

 in a mineralogical sense it is advantageously changed for Basalt, 

 Greenstone, Felsparite, Sienite, Serpentine, Diallage Rock, &e. 



TRAPA, a genus of Plants belonging to the natural order Onagracea;. 

 The fruit of Trapa is furnished with cpines, and the species are 

 commonly called Water-Caltrops, from the plants floating on the 

 surface of lakes, and on that of slow-running waters. They are found 

 in the temperate parts of Europe and of Siberia, in Cashmere, India, 

 Cochin-China, and China. The genus is characterised by having a 4- 

 parted adherent calyx ; petals and stamens 4 ; ovary 2-celled, witli 

 solitary pendulous ovules. The fruit is hard, indehiscent, 1 -celled 

 and 1-seeded. The seed is large and exalbuminous; the two cotyle- 

 dons very unequal. The floating habit and clustered leaves easily 

 distinguish these plants. The leaves under water are cut into capillary 

 segments, and the petioles are tumid in the middle. 



T. natam, the European species, is remarkable for its fruit with 4 

 spines, being of a blackish colour and large size, and its seed, which 

 nearly fills it, being farinaceous, and good to eat, whether raw, roasted, 

 or in soups, and is somewhat like a chestnut in taste. It was known 

 to the Romans by the name Tribulus. Pliny says (lib. xxi., c. 58), 

 "About the rivers Nilus and Strymon the inhabitants gather it for their 

 meat" 



T. ln.-/:i,i<tfi, Roxb. (' < 'on. in. PI.,' ii. 234), has the nut with two 

 opposite, straight, barbed, spinous horns, noticed by Sir W. Jones 

 under the Sanscrit name of Sringata : it is commonly known all over 

 India by the name Singara, both names having reference to its horned 

 appearance. It is also found in the Lake of Cashmere. In India the 

 nuts are sold in all the bazaars, as their farinaceous kernels are much 

 esteemed by the Hindoos. A species called by the same name, 

 Singhara, forms a considerable portion of the food of the inhabitants 

 of Cashmere. 



T. bicornit is distinguished from the last by its two horns being 

 recurved and very obtuse. It is carefully cultivated in lakes, ponds, 

 and other receptacles of water. 



TRA'PELUS, Cuvier's name for a genus of Lizards which have the 

 form and teeth of the Ayanue, but their scales are small and without 

 spines. They have no pores on the thighs. 



Tra/ieliu /Ksypliui (Agama mulal/ilii, Merrem.). 

 BAT. HMI. OIV. VOL. IV. 



T. ^Egyptius is a small reptile, which sometimes puffs out its body, 

 whence the name of orbicularis, Daudin. It is also remarkable for its 

 changes of colour, heuce it is called by the French Le Changeaut 

 d'Egypte. 



TRASS. A deposit of volcanic ashes and scoria: thrown out from the 

 Eifel volcanoes, and accumulated in vallej's and old lakes under the 

 influence of water, is thus designated. It is equivalent, or nearly so, to 

 the Puzzolana of the Neapolitans. (Lyell's ' Principles of Geology.') 



TRAVELLER'S JOY. [CLEMATIS.] 



TRAVERTIN, the Italian term for Concretionary Limestone, pro- 

 duced from springs holding carbonate of lime in solution. 



TREACLE-MUSTARD. [ERTSIMUM.] 



TREE, COTTON. [GOSSYMUM; BOMBAX.] 



TREE-FERN. [CYATHEA.] 



TREE-FROGS. [AMPHIBIA.] 



TREE-MALLOW. [LAVATERA.] 



TREES. [EXOGENS ; AGE OF TREES.] 



TREFOIL. [TniFOLiuM.1 



TREFOIL, BIRD'S-FOOT. [Loius.] 



TREMANDRA'CE^E, Poreworte, a natural order of Exogenous 

 Plants, consisting of slender shrubs very much resembling heaths, usually 

 covered with glandular hairs. The leaves are without stipules, either 

 alternate or whorled, entire or toothed. The flowers are often large 

 and handsome, seated on solitary axillary pedicels. The calyx has 4 

 or 5 sepals with a valvate estivation ; the petals equal in number to 

 the sepals and much larger ; the stamens hypogynous, double the 

 number of the petals, with anthers 2- or 4-celled, opening by a pore 

 at the apex ; ovary 2-celled, with a simple style and stigma ; seeds 

 pendulous, and furnished with a caruncle at the apex ; albumen fleshy, 

 in the axis of which lies a straight cylindrical embryo. 



This is an order of Australian plants, containing but two geuera, 

 Tetratheca and Tremandra. 



3 4 1 



Tetratheca glandulota. 



1, cutting with flowers; 2, ovary with simple stigma; 3, 4-cellcd anther; 

 4, anther opening by a simple pore ; 5, section of capsule showing its two cells ; 

 6, seed with the caruncle and embryo lying in albumen. 



TREMATODA. [ENTOZOA.] 



TREMELLA. [TUEMELLINI.] 



TREMKLLI'NI, the name of the last order of the Cohort ttymeno- 

 mycetes in Friea's arrangement of the natural order Piatgi. Tlie typo 

 of this order is the Tremella, a genus constituted by Dillenius, and 

 applied to a variety of forms of Fungi belonging to this group, but 

 now arranged under other genera. The Tremella of Dilleuius included 

 all kinds of the lower forms of plants which possessed a gelatinous 

 character; and as these exhibited a tremulous motion on being shaken, 

 tlie gave them this name. It was for a long time a matter of dispute 

 among botanists as to where the Tremettce should be placed. Lin- 

 nuiUR arranged them with the A Igce, Persoon with the Fungi, and Smith 

 as Algce Amliguui. As however their nature became better understood, 

 many anomalous forms were removed from among them ; and several 

 genera having been formed, they are now arranged among the Fungi. 



The plants of this order are known by their amorphous character, 

 having a soft gelatinous appearance, and looking like gummy exuda- 

 tions of the substances on which they grow. Their sporidia are free. 

 They have been at various times objects of superstition, and have also 

 been employed in medicine. In the wooded countries, where they are 



