thal] 



Ef)e Crcatfttrp at Untaug. 



1138 



nical Miscellany :— ' The ocean hardlyboasts 

 a more beautiful production than this ; it 

 is generally about the height of a man, 

 very bushy and branched, each branch 

 bearing a broad leaf at its extremity, 

 which unfolds spirally, and by this gradual 

 development produces the stem with its 

 branches and lateral divisions. A spiral 

 border wound round the stem indicates 

 the growth of the frond. The frond pre- 

 sents a convex bent lamina without nerves; 

 or to a certain degree a leaf of which one 

 half is wanting, for the stem may be con- 

 sidered as an excentric nerve. A number of 

 long rather narrow perforations, arranged 

 in a radiate form, give the frond the ap- 

 pearance of a cut fan ; these perforations 

 being coeval with its formation, and appa- 

 rently not owing to inequalities of sub- 

 stance. At first these perforations, which 

 are situated near the stem, and where the 

 frond is bent in, are round, and have their 

 margins turned outwards ; but by the sub- 

 sequent growth of the frond they become 

 longer, and their margins disappear. In 

 the middle of the frond they are like true 

 clefts ; but nearer the margins, from the 

 greater development of the leafy substance, 

 they are more contracted in their breadth, 

 and therefore seem round. The frond has 

 a complete and entire margin, but is fre- 

 quently torn; its substance is coriaceous. 

 The root resembles that of the larger La- 

 minarice, but is more woody.' T. Clathrus 

 is abundant on the shores of Russian Ame- 

 rica in the Bay of Illuluk, which it clothes 

 like a thick hedge for a space of sixty or 

 eighty feet from the land. [M. J. B.] 



THALASSIOPHYTA. A name used by 

 Lamouroux for Algce, but inapplicable 

 from its being too restricted, and exclud- 

 ing all fresh-water species. [M. J. B.] 



THALAY, THAULAY. Indian names 

 for the fibre of Pandanus odoratissimus. 



THALIA. A genus of Zfarantacece, com- 

 prising certain herbaceous plants, natives 

 of Tropical and Extratropical America. 

 The leaves are stalked, and covered with 

 powdery bloom like that on a plum. The 

 flowers are borne on a stalked panicle, and 

 are concealed between two bracts. The 

 calyx has three segments, the corolla six ; 

 the three outer of these nearly equal, the 

 three inner unequal; one having a slight 

 stalk, another two thread-like processes 

 at the base, and the intermediate one or 

 lip hooded and semicircular. The single 

 thread-like stamen is attached to the inner 

 petal, that has the two processes at the 

 base. The ovary is inferior one-celled, and 

 contains a single ovule, attached to its 

 base. The style is thick, twisted spirally, 

 and the stigma is somewhat two-lipped. 



T. dealbata is an elegant aquatic plant, 

 native of South Carolina. Its fine glaucous 

 folia.se and elegant panicles of purple flow- 

 ers render it a very desirable plant for 

 aquaria. It will even resist our winters. 

 The structure of the leafstalk in this plant 

 is curious, and has not been described 

 fully. In the interior are a number of air 



canals' having at intervals horizontal par- 

 titions, consisting of beautiful star-shaped 

 cells. Traversing the air-canals, and pass- 

 ing between the rays of the star-like cells, 

 are bundles of woody tissue, which may 

 be seen even by the naked eye. Under the 

 microscope these wood-cells or fibres are 

 seen to be here and there marked by little 

 tubercles, apparently the remains of cel- 

 lular tissue ruptured by the disproportion- 

 ately rapid growth of the two kinds of 

 tissue, cellular and woody. [M. T. M;] 



THALICTRUM. A well-marked genus of 

 herbaceous plants belonging to the Ranun- 

 culacece, distinguished among its allies 

 by the absence of petals and of appen- 

 dages to the fruit. Amongst the best-known 

 species is T. aquilegifolium , the Feather 

 Columbine (Pigamon d fenilles d'Angolie or 

 Columbine plumeuse of the French), arobust 

 bushy herbaceous plant, with glaucous 

 leaves tinged with purple, and large pa- 

 nicles of flowers, which though destitute 

 of petals are rendered conspicuous by the 

 numerous stamens with long slender fila- 

 ments and large sulphur-coloured anthers. 

 It is a native of the Alps, and is commonly 

 grown in shrubberies and old-fashioned 

 gardens. T, glaucum, a yet more robust 

 plant of similar habit, is a native of Spain, 

 and is also a handsome plant. 



There are three British species: T.flavum, 

 trje Common Meadow- Rue, atall plant with 

 glaucous bipinnate leaves, and compact 

 panicles of erect flowers, conspicuous by 

 their yellow stamens, frequent in moist 

 meadows and by the banks of rivers ; T. 

 minus, with leaves three to four times pin- 

 nate, and diffuse panicles of drooping 

 flowers, mostly found in chalky or magne- 

 sian thickets ; and T. alpinum, from ten to 

 twelve inches high, with twice ternate 

 glaucous leaves, and simple stems bearing 

 a raceme composed of a few drooping flow- 

 ers. Among the numerous exotic species, 

 besides those mentioned, several are to be 

 met with in English gardens, the foliase 

 of all of which more or less resembles in 

 character that of the Common Columbine. 

 French: Rue des pres; German: Wiesen- 

 raute. [C. A. J.J 



THALEODES. Of or belonging to or 

 proceeding from a thallus. 



THALT.OGENS. A name applied by 

 Lindley and others to comprise those 

 cryptogams which are extremely simple 

 in their structure, and exhibit nothing like 

 the green leaves of pha?nogams. In the 

 few cases in which there are leaf-like ex- 

 pansions they are not arranged symmetri- 

 cally round a stem, and are destitute of all 

 trace of stomates and breathing pores. 

 In a very few cases only is there anything 

 like trachea?, and then only as local organs 

 and constituting no part of the general 

 mass ; while in those lichens or Algce 

 whose stems are of long duration, thoutrh 

 there may be something like centrifugal 

 growth indicated by zones, it is of a totally 

 different nature from that of acrogens. 

 The most definite point of distinction, 



