TIIELIDIUM. 



[ '65 ] 



TJIYRSOPORELLA. 



BiBL. Duiiirdin, Infus. 323. 



TnELID'lUM,-Mass.— A geuus of Micro- 

 liehtnis parasitic on the thallus of Lecauor*. 



Char. Spores subfiisiforiu, 2-looTilar, co- 

 lourless. (Lindsay. Qu. J\Iic. Jn. 18Gil, 340.) 



THELOCAR'PON, Nvl.— A geuus of 

 Pyronodei (Lichenaceous Lichens). 



Four species. (Leighton, Lich. Fl. 439; 

 Lindsay. Qu. Mic. Jn. 1809, 345.) 



THELOTREMA, Ach.— A genus of Pla- 

 coidei (Lichenaceous Lichens), containing 

 two British species. (Lei^hton, Lich. Fl. 

 238.) 



THEO'RUS, Ehr.— A genus of Rotatoria, 

 of the family Hydatinaea. 



Char. Eyes colourless, more than three, 

 cervical, in two gi-oups ; foot forked ; jaws 

 each with a single tooth. 



T. vernalis (PL 44. fig. 32). Toes small, 

 frontal hook absent. Aquatic; length 1-140 

 to 1-120". 



T. uncinaUts. Toes long, frontal (or 

 rather cervical) region with hooks ; fresh- 

 water ; length 1-240". 



BiBL. Ehr. Inf. 454 ; Pritchard, Inf. 000. 



THLIPSU'RA, J. & H.— A Cytheroid 

 Ostracode in the Silurian strata. (Jones 

 and HoU, Ann. N. H. 4. iii. 213.) 



THO'REA, Bory.— A genus of Batra- 

 chospermese (Confervoid Algte), of which 

 one species (T. ramosisshna) occurs in Bri- 

 tain; its fronds are olive-black, branched 

 filaments, a foot or more long, about as thick 



740. 



Thorea ramosiasima. 

 Horiisontal section of a filament (halved). The semi- 

 circular denser portion represents the axis, the loose 

 spreading branches the villi. Magnified 25 diameters. 



as a crow-quill, with a villous siu-face. The 

 filaments are composed of radiating branched 

 cells, closely compacted into a kind of solid 

 axis, from which proceed lax, radiating ra- 

 muli, forming the villous surface. The 

 spores or sporangia! cells arise from these 

 ramules (fig. 740). 



BiBL. Kiitz. Phyc. qeneralis, pi. 16, Sp. 

 Alg. 534 ; Emi. Bot. Supp. No. 2948 ; Has- 

 sail, Alg. 64; Rabenht. Ahj. iii. 418, 



THOREL'IJA, Boeck. — A genus of 

 Copepodous Entomostraca. T. hrunnva, on 

 Laminaria. (Brady, Copep. i. 95.) 



TIIUIA'RIA, Flem.— A genus of Polypi, 

 of the Order Ilydroida, and family Sertiila- 

 riid;v. 



Char. Those of Sertularia ; but the colls 

 closely pressed to or imbedded in the stem 

 or branches. Two species : 



T. thuia. Cells ovate-elliptical, acutish ; 

 vessicles pear-shaped. On shells from deep 

 water. 



T. articulata. Cells ovate, obtuse or trun- 

 cate, vesicles elliptical ; rare. 



Bibb. Johnston, Br. Zooph. 83 ; Gosse, 

 Mar. Zool. ii. 23; Iliucks, Iii/d. Zooph. 



THU'JA, L.— A geuus of tjoniferte (Gym- 

 nospermous Plants), to which belongs the 

 arbor vitcc of gardens, Thuja occidentalis ; 

 T. oricntalis is placed by some authors under 

 another genus, Biota. The characters of 

 Coniferous wood, Gymnospermous ovules, 

 &c., may be observed in tliese plants (see 

 CoNiFERiE and Ovulk). 



THURAjM'MINA, Brady.— a subglobu- 

 lar Arenaceous Foraminifer (0"5 mm.), with 

 perforate papillfe ; single and enclosing a 

 smaller chamber or group, and adherent. 

 Atlantic and Pacific. (H. B. Brady, Q. Jn. 

 M. Sc. n. s. xix. 45.) 



THURIC'OLA, Kt.— A genus of Peritri- 

 chous Infusoria. Like Vaginicola, but sheath 

 with a closeable valve. Three species; salt 

 and fresh water. (Kent, /;//. 718.) 



TH Y'AS, Koch. — A genus of Hydrachnea 

 (Acarina). Like Ilyclraclina, but legs formed 

 for w^alking. T. venusia. (Koch, Uebers. ; 

 Murray, Fc Frit., fig.) 



THYMELEA'CE^.— An order of Di- 

 cotyledons to which the Spurge-Laurels 

 {Daphne) belong. In D. Lar/etto ( = Lagetta 

 lintearia) the fibres of the liber are separated 

 into lozenge-shaped meshes, arranged in 

 such beautiful and easily-separable layers, 

 as to have acquired for the plant the name 

 of the Lace-Bark Tree. 

 See Liber. 



THYRSOPOREL'LA, Giimb.— Gumbel 

 ' divides the Factyloporidcce (see Dactylo- 

 : pora) into (I.) those with chambers : — 

 I 1. Ilaploporella ; segmental, annular, or 

 i cylindrical (piled rings), with large cham- 

 I bers and simple traversing canals (0 species, 

 recent and Tertiary) : 2. IJavtyloporella ; 

 cylindricnl, with large and subsidiary cham- 

 bers, and branched traversing canals (4 

 species, Tertiary). (II.) Those without 

 chambers: — 3. Thy rsoporella ; cylindiical, 



