WOOL. 



[ 823 ] 



XYLARIA. 



WOOL OF Animals. See HAin. The 



fibvt\s (if wool are coloured by the test- 

 liquids of Millou aud Schultze. 



WRANGE'LIA, Ap-.— A peiius of Cera- 

 raiaceiie (Florideous Alga)), differing- from 

 Qrtffithmn chietly iu the scattered tetra- 

 spores. W. miilfiji'hi, the only Britisli spe- 

 cies, has rose-red feathery fronds, an inch 

 high, consistiug of a main filament, about 

 as thick as a bristle, composed of a single 

 row of cells, bearing long, pinnately-ar- 

 ranged, patent branches, mostly branching 

 in the same way again. At the articula- 

 tions occur two opposite (or more rarely a 

 whorl of) pinnato-multifid or subdichoto- 

 mous ramelli 1-1:^ to l-li" long. The fruc- 

 tification consists of: — 1, favellce, borne on 

 stalks at the joints, and surrounded b}' a 

 whorl of ramelli; and 2, elliptical fetra- 

 spores, opposite, secund or tufted, ou 

 the lower part of the ramelli. In some 

 foreign species antheridia have been ob- 

 served in similar situations to the tetra- 

 spores. 



BiCL. Harvey, Mar. Alg. 169, pi. 24 D ; 

 Phyc. Brit. pi. 27 ; Derbes and Solier, Ann. 

 Sc. Nat. 3. xiv. 273, pi. 35 ; Thuret, ibid. 4. 

 iii. 38. 



X. 



XANTHID'IA.— The bodies found in 

 flint, and thus called, are probably sporangia 

 of Desmidiace* (PI. 25. figs. 22-28). They 

 have been distributed in genera and species, 

 the description of the characters of which 

 would be useless. 



It is a curious circumstance, that these 

 sporangia should be found in flint, which is 

 of marine origin, considering that tlie Des- 

 midiacete are none of them marine. 



XANTHIDTUM, Ehr.— A genus of Des- 

 midiacess, 



Cliar. Cells single, constricted in the 

 middle ; segments compressed, entire, spi- 

 nous, with a circidar, usually tuberculated 

 projection near the centre. Spines more 

 til an two to each segment. 



X. armatum (PL 14. fig. 23; fig. 24, 

 empty cell, showing the projections). Seg- 

 ments broadest at the base ; spines short, 

 stout, tri- or multi-fid ; length 1-180". 



X. fasciculafum (PI. 14. fig. 25). Seg- 

 ments with from four to six pairs of subulate 

 marginal spines; central projections minute, 

 conical, and not beaded ; common ; length 

 1-400". 



Sixteen .species. 



BiBL. Ralfs, Br. Desmid. Ill; Rabenht. 

 Ah/, iii. 221 ; Archer, Prifc/iard's In/us. 



XANTIIIOPYX'IS, Klir.-A genus of 

 fossil Diatomacete, consolidated with Pyxi- 

 DicuLA. It consisted of those species the 

 margins of the valves of which are furnished 

 witli a dentate membrane, or the surface 

 covered with seto^ or hair-like processes. 

 Bermuda. 



BiRL. Ehr. Ber. Berl. ^A.w/. 1844, 2(34; 

 Kiitz. Sp. Alg. 23 ; Pritchard, Lifns. 82G. 



XENOD'dCIlUS, Schlecht— A genus of 

 Urediuei (Flypodermous Fungi), con.sisting 

 of black tufts, found on the leaves of Pote- 

 rium, containing microscopic, short, curved, 

 usually shortly stipitate filaments, attenu- 

 ated at each end, composed of a moniliforra 

 row of (five to fifteen) globose cells filled 

 with black granules. 



These bodies occur associated with TJredo 

 miniata, of which X. carhonarius appears to 

 be the perfect form. Xenodochus is only 

 distinguished from Phragaiidium by the 

 greater number of joints. 



BiBL. Schlechtendahl, Li7incea, i. 237, 

 pi. 3. fig. 3 ; Fries, Sum. Vet/. 505 ; Ber- 

 keley, Ann. X. H. i. 263. 



XENOSPHyE'RIA, Trevis.— A genus of 

 Micro-lichens, parasitic on the thallus of 

 Solorina saccata. 



Char. Spores 6-8, oblong, 4-6-locular, 

 brown ; sometimes large, irregulai', and 

 muriform. 



BiBL. Korber, Syst. 326; Lindsay, Qu, 

 Mic. Jn. 1869, 344. 



XESTOLEBE'RIS, Sars. — One of the 

 CyiheridcB, with subtriangvdar valves,higher 

 behind than in front, smooth, with distant 

 papillse ; lower antennoe with 4 joints; 

 upper 6-jointed, with simple setje, and 

 short. Two living British species, com- 

 mon. 



BiBL. Brady, Tr. Linn. Soc. xxvi. 437. 



XIPHIAS'TER, Murray.— A genus of 

 Ixodea (Acariua). Flat, with a long pro- 

 jecting rostrum and long applied palpi ; 

 abdomen beaded behind. X. rostratum, 

 Old Calabar. (Murray, Ec. Entom. 201, 



fig.) 

 XIPHICHI'LUS, Brady.— One of the 



Cytheridce, near Parado.vostoma ; with sub- 

 equal, compressed-valves, elongate, pointed, 

 thm, aud smooth. Two living British spe- 

 cies, rare. (Brady, Nat. Hist. Tr. North. 

 S,- Durh. iii. 369). 



X YL A'RI A, Schrank. — A genus of Sphae- 

 riacei (Ascomycetous Fungi), several of 

 which are common ou rotten wood, stumps 



