MYRIONEMACEiE. 



[ 629 ] 



MYXOMYCETES. 



MYRIOXEMA'OE.E.— A family of Fu- 

 coide;^. Olive-coloured sea-weeds, with a 

 tuber-shaped or crustaceous spreading froiitl, 

 sometimes minute and parasitical. _ Ovoid 

 uiiiloculiU", and iilamentous multilocular 

 sporanges attached to the superficial tila- 

 ments, and concealed among them. 



Leathesia. Frond tuber-shapad. 



Ralfsia. Frond crustaceous. 



EU'whlstea. Frond parasitical, consisting 

 of a tubercular base bearing pencilled erect 

 filaments. 



Miirionema. Frond parasitical, forming 

 a flat base, bearing cushion tufts of decum- 

 bent fllaments. 



MY^RIOTHE'LA, Sars.— A genus of 

 Hydroid Zoophytes. 



^Char. Polj-pes soUtary, cylindrical, ter- 

 minating in a conical pro*boscis, springing 

 from an adherent chitinous base; tentacles 

 small, capitate, covering the greater portion 

 of the body ; gonophoves clustering round 

 the base of the polypes, and containing 

 fixed sporosacs. M. Phryriia, on stones. 



BiBL. Sars, Zool. Seise in Lofoten ; Gosse, 

 Mar. Zool. 19 ; Hincks, Ht/d. Zooph. 75. 



MY'RIOTRICH'IA, Harv.— A ^enus of 

 Ectocarpaceas (Fucoid Algae), consisting of 

 minute epiphytic plants, forming tufts of 

 capillary filaments on larger Algfe. Fila- 

 ments simple jointed tubes, set all over with 

 minute, simple, spore-hke ramules, which 

 again are clothed with very slender, long, 

 jointed filaments. Fructification composed 

 of oval unilocular sjwranges on the sides of 

 the main axis, producing zoospores ; pro- 

 bably also multilocular sporanges exist. 



M. daviformis. Main filament with quad- 

 rifarious ramules, increasing in length up- 

 wards ; fronds 1-2" long, forming tufts on 

 Chorda lomeniaria. 



M.jiliformis. Main filaments very long, 

 often flexuous, set at irregular intervals 

 with oblong clusters of minute papilliform 

 ramules; 1" or more long; on Chorda lo- 

 nientaria and Aspei-ococais echinatus. 



BiBL. Harv. PJiyc. Br.; Mar. Aly. 0-3; 

 Hook. Jn. Bot. i. 300. 



MY^ROTHE'CIUM, Tode.— A genus of 

 Stilbacei (Hyphomycetous Fungi). 



M. roridum, Tode, occurs on decayed 

 plants, fungi, &c. It has no peridium, but 

 consists of minute subcylindrical spores 

 seated on a thin base, the whole forming a 

 subgelatinous mass, wliich is exactly analo- 

 gous to the fructifying mass of Phalloidei. 



BiBL. Berk. Br. FL ii. pt. 2. .323 ; Fries, 

 Stim. Veg. 448 ; Cooke, Handb. 559. 



MYXAS'TllUM, Ilaeckel.— A genus of 

 Monera. 



Char. A simple shapeless protoplasm 

 body without vacuoles, which protrudes 

 simple or ramifying and anastomosing pro- 

 cesses. Reproduction by radial fission. The 

 encapsuled resting body divides into a groat 

 number of germs, whose longitudinal axis 

 is radially directed towards the centre of 

 the globular cyst. Each separate germ sur- 

 rounds itself with a siliceous covering. The 

 germs issuing from these spore-coverings 

 at once assume the form of the full-grown 

 organism. 



M. radians, Lanzerote, Canaries. 



BiBL. Haeckel, Monog. of Monera {Qii,. 

 Mic. Jn. ix. n. s. p. 342). 



MYXODIC'TYUM, Haeckel.— A genus 

 of Monera. Simple protoplasm bodies with- 

 out vacuoles ; pseudopodia ramifying, ana- 

 stomosing, and forming a net. Reproduc- 

 tion probably by division, each individual 

 producing new colonies. M, sociale. Bay 

 of Algesiras. 



BiBL. Haeckel, Monera ( Qu. Mic. Jn. ix. 

 n. s. 339). 



M YXOQAS'TRES = Myxomycetes. 



M YXOM YCE 'TES.— A family of minute 

 Fungi, of cm'ious and interesting structure, 

 characterized by their development from a 

 mucilaginous filamentous matrix, out of 

 which arise sac-like dehiscent sporangia or 

 peridia, emitting a very remarkable, often 

 reticulated, filamentous structure, bearing 

 the spores. 



The Myxomycetes grow upon bark of 

 trees, decayed wood, or on leaves (especially 

 imder certain atmospheric conditions), or on 

 the ground ; and their evanescent mycelium 

 consists of diflluent mucilaginous proto- 

 plasmic filaments of varied form and colom'. 

 In proportion as these acquire consistence, 

 there is formed a crust common to the 

 whole mass, divided within into chambers, 

 or a number of individuals appear separate 

 from it and associated on a common thal- 

 lus. In the first case a single peridium is 

 formed, which may be regarded as a com- 

 mon peridium if we consider the inner cells 

 as partial peridia soldered together, while 

 in the second case each individual has its 

 own peridium. This peridium, sessile or 

 stalked, is composed of one or more mem- 

 branous, papery, or crustaceous coats; in 

 some cases where there are two coats, tho 

 outer is crustaceous and persistent, or it is 

 extremely thin and membranous, and breaks 

 up into deciduous scales. In the outer waU 



2 m 



