MEMBRANIPORA. 



[ 499 ] 



MERfDION. 



the appearance of an undulating membrane 

 arises from the existence of a fibre coiled 

 around the spermatozoa, and undulating 

 throughout its length (PI. 50. fig. 17). 

 This opinion is based upon the circumstance 

 that if the coiled fibre be detached from the 

 proper filament of a spermatozoon or sper- 

 matozoid, no margins of the (lacerated) 

 membrane can be detected other than that 

 visible at first, and which really represents 

 the coiled fibre. This, however, is an in- 

 teresting subject for further investigation. 

 Siebold, who has paid most attention to it, 

 remarks that Trypanosoma Grubii, a sup- 

 posed entozoon found in the blood of frogs 

 and fishes, is not an independent animal, 

 but simply an undulating membrane swim- 

 ming freely. 



BIBL. Siebold, Sieb. und Kb'll. Zeitschr. 

 Bd. ii. 356, and the Bibl. therein. 



See Mucous and SEROUS MEMBRANES. 



MEMBRANIPORA, Johnst. A genus 

 ofmarinePolyzoa,familyMEMBRANTPORiD^3. 



Several British species; usually found in- 

 crusting sea- weeds, more rarely shells and 

 stones. 



M.pilosa (PL 41. fig. 18). Orifices of the 

 cells with one long hair, and several spinous 

 teeth. Verv common. 



MEMBR ANIPOREL'LA, Blainv., =Le- 



aliaj pt. (Hincks, Polyz.\ 



MEMBRANIPOR'ID.E. A family of 

 Cheilostomatous Infundibulate Polyzoa. 



Distinguished by the expanded, incrust- 

 ing, stony polypidom, and the horizontal 

 quincuncial cells. Genera : 



Membranipora. Cells open in front, with 

 raised margins. 



Lepralia. Cells closed in front, poly- 

 pidom spreading circularly. 



BIBL. Johnston, Br. Zooph. ; Busk, Cat. 

 Mar. Polyz. ; Gosse, Mar. Zool. ii. 16 ; 

 Hincks, Polyz. 127. 



MENI'PEA, Lamx. A genus of Infun- 

 dibulate Cheilostomatous Polyzoa, family 

 Cellulariadse. 



Char. Cells oblong, tapering downwards, 

 not perforate behind, with one or two sessile 

 birds'-heads in front below the orifice. Two 

 British species. 



M. ternata (Cellidaria ternata, Johnst.). 

 Cells elongated, greatly tapering down- 

 wards, 3 in each internode, with a stalked 

 operculum protecting the orifice ; operculum 

 expanded, entire, two spines on the upper 

 margin ; anterior birds'-head single. 



BIBL. Johnston, Br. Zooph. 335; Busk, 

 Cat. 20 ; Hincks, Polyz. 36. 



MENIS'CIUM. A genus of Grammi- 

 tideae (Polypodiaceous Ferns). 



10 sp. ; tropical. (Hook., Syn. 390.) 



MENISCOS'TOMUM, Kt. A genus of 

 Holotrichous Infusoria. Like Paramecium, 

 but mouth lateral, lunate ; with a vibratile 

 membrane. 1 sp. ; fr. wat. (Kent, Inf. 539.) 



MENIS'PORA, Pers. A genus of Mu- 

 cedines (Hyphomycetous Fungi), one species 

 of which, M. lucida, Corda, is recorded as 

 British, growing on decayed wood. 



BIBL. Berk, and Broome, Ann. N. If. 

 2 ser. vii. 101 ; Corda, Ic. i. pi. 4. fig. 223. 



MENOID'IUM, Perty. A genus of 

 Flagellate Infusoria. 



Char. Small, crescentic, thicker on the 

 outer margin, colourless, or greenish. 



M. pellucidum, freshwater ; movement 

 jerking and revolving, 1-670 to 1-430". 



BIBL. Perty, Lebensf. 174. 



MENOPON, Nitzsch. A subgenua of 

 LIOTHEUM (Anoplura); with the head 

 semilunar or trapezoidal, but without a deep 

 lateral sinuosity. The species infest poultry, 

 the partridge, quail, &c. 



MEREN'CHYMA. A name applied by 

 some authors to the form of vegetable cel- 

 lular tissue where the cells are of circular, 

 ellipsoidal, or irregularly rounded outline; 

 ordinarily known as lax parenchyma. 



MERID'ION, Leibl. A genus of Diato- 

 macese. 



Char. Frustules (in front view) wedge- 

 shaped, united laterally so as to form seg- 

 ments of circles or spiral bands. Fr. wat. 



Frustules in side view obovate, and fur- 

 nished with coarse transverse stria? visible 

 under ordinary illumination, which extend 

 into the front view. 



Kiitzing distinguishes Meridian, in which 

 the frustules form a spiral (helical) band, 

 from Eumeridion, in which they form a con- 

 volute band. 



Meridion circulare, Ag. (PI. 17. fig. 7 : 



a, front view ; b, side view). Frustules in 

 side view simply obovate, forming a spiral 

 (helical) band or filament ; length of frus- 

 tules 1-600 to 1-375". 



Meridion constrictum, Kg. (PI. 16. fig. 28, 

 filament flattened, and frustules (front view) 

 separated by drying ; a, convolute filament ; 



b, side view). Frustules in side view con- 

 stricted near the broad end, attenuate to- 

 wards the narrow end, and attached to a 

 hemispherical stipes or cushion. 



BIBL. Kiitz. Batill. 41. Sp. Alg. 10; 

 Ralfs, Ann. N. H. 1843, xii. 457 ; Smith, 

 Br. Diat. ii. 5 ; Rabenh. Alg. i. 295. 



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