TETRAGRAMMA. 



[ 639 ] 



THECAMONADINA. 



to differ considerably in structure from the 

 parent-valves. 



BiBL. Ralfs, Ann. Nat. Hist. 1843. xii. 

 105; Kiitzing, Sp.Alg. 118. 



TETRAGRAMMA, Elir. = Terpsinoe. 



TETRANYCHUS, Duf. — A genus of 

 Ai'achnida, of the order Acarina, and family 

 Trombidina. 



Char. Pal])i incumbent upon the rostrum, 

 stout, short and conical; mandibles and 

 labium as in Raphignathus ; coxse inserted 

 in two groups on each side, one for the two 

 anterior, the other for the two posterior; 

 anterior legs longest, third joint (femur) 

 largest ; claws short and greatly curved. 



Several species. 



T. glaher (PL 2. fig. 32). Very minute ; 

 eyes two, whitish, upon the antero-lateral 

 portion of the trunk. Under stones in damp 

 places. 



r. lapidum (PI. 2. fig. 35). Legs slender, 

 anterior verj' long ; eyes three on each side ; 

 several rows of white points upon the back 

 and margins of the body. Found under 

 stones and upon plants. 



BiBL. Duges, Ann. d. Sc. nat. 2 ser. i. 

 24, & ii. 55 ; Gervais, WalcTcenaer^s Apteres, 

 iii. 165; Dufour, Ann. des Sc. nat. 1 ser. 

 XXV. 2/9 ; Koch, Deutschl. Crustac, 



TETRAPHIS, Hedwig.— A genus of 

 Mosses. See Georgia. 



TETRAPLOA, Berk, and Br.— A genus 

 of Torulacei (Coniomycetous Fungi), com- 

 prising at present a single species, T. aris- 

 tata, a curious little fungus growing upon 

 leaves of grass, forming an olive-coloured 

 stratum composed of bodies consisting of 

 fom' connate quadri-articulate spores, each 

 terminated by a bristle. 



BiBL. Berk. & Br. Ann. Nat. Hist. ser. 2. 

 V. p. 459.pl. U.fig. 6. 



TETRAPLODON, Br. and Sch.— Agenus 

 of Splachnacese (Acrocarpous operculate 

 Mosses), containing some of the Splachna 

 of authors. 



Tetraplodon angustatum, Br. and Sch. = 

 Splachnum angustatum, Linn. fil. 



T. mnioides, Br. and Sch. = Spl. mnioides, 

 Linn. fil. 



TETRASPORA, Link.— A genus of Pal- 

 mellaceae (Confervoid Algae), nearly related 

 to the Ulvacese ; indeed it is very difficult to 

 draw any very distinct line of demarcation 

 between Tetraspora and Monostroma, the 

 fronds of both of which are membranous 

 strata formed of a single layer of cells; the 

 latter, however, has its constituent cells 

 crowded, while in Tetraspora the green * cell- 



contents' lie scattered, mostly in groups of 

 two or four, in the gelatinous frond. Thuret 

 states that the primordial utricles of the cells 

 possess long cilia in the stage when they are 

 imbedded in a continuous frond (PI. 3. fig. 10). 

 The history of development of this genus is 

 imperfectly kno^^•n at present ; the ciliated 

 cell-contents break out as swarming zoo- 

 spores, but their next following changes have 

 not been observed. Two recorded British 

 species appear to be distinct, growing in 

 stagnant pools (see Monostroma, Meris- 

 MOP^DiA, and Sarcina). 



1. T. gelatinosa (PI. 3. fig. 10). Frond 

 gelatinous, soft, of irregular shape and divi- 

 sion, pale green; cells" 1-10800 to 1-4200" 

 in diameter (Kiitzing, Tab. Phyc. i. p. 28). 



2. T. lubrica. Frond green, elongated, 

 mesentery-shaped, lobed and sinuatecl, lobes 

 often anastomosing; cells angulo-globose, 

 1-3600" in diameter (Kutzing, /. c. pi. 30). 



BiBL. Hassall, Brit. Fr. Alg. p. 300. pi. 

 78 ; Kutzing, Sp. Alg. p. 225, Tab. Phyc. i. ; 

 Thuret, Ann. des Sc. nat. 3 ser. xiv. p. 248. 

 pi. 21; Nageli, Einzell. Alg. p. 71. pi. 2. 



TEXTULARIA. See Foraminifera 

 (p. 271). 



THAMNOMYCES, Ehr.— A genus of 

 Spjiaeriacei (Ascomycetous Fungi). T. hip- 

 potrichoides is referred by Fries to Rhizo- 

 morpha. It appears to require further ex- 

 amination. 



BiBL. Berk. Brit. Flor. ii. pt. 2. p. 284 ; 

 Fries, Summa Veg. 382. 



THECA. — A term used very loosely in 

 the descriptions of Cryptogamic plants. In 

 the case of the Lichens and Fungi it is syn- 

 onymous with Ascus, a sac in which free 

 spores are developed ; these are called theca- 

 spores or ascospores in contrast with basi- 

 DiosPORES or stylospores. In the higher 

 Cryptogamia, as Ferns, &c., it is used in the 

 sense of sporangium. 



THECAMONADINA, Duj.— a family 

 of Infusoria (= Ciyptomonadina and some 

 Astasiffia, E.). 



Char. Usually coloured ; covered with a 

 non-contractile tegument, which is either 

 hard and brittle, or membranous ; no other 

 locomotive organs present than one or more 

 flagelliform filaments. 



The organisms probably consist of Algae, 

 or their spores. They are minute, usuallv 

 green, but some are red ; and they often 

 colour stagnant water from existing in vast 

 numbers. They are mostly recognisable by 

 their rigidity and the uniformity of their 

 motion. 



