EPHEBE. 



[ 235 ] 



EPHEMERID^. 



considerable part of the inferior cornua, and 

 of the lateral ventricles. It consists of a 

 layer of delicate cihated epithelium, situated 

 either immediately upon the cerebral sub- 

 stance, or upon an intermediate layer of 

 areolar tissue, or of a soft, homogeneous or 

 granular mass. The cells are nucleated, and 

 vary in diameter from 1-960 to 1-490"; 

 they sometimes contain pigment. 



The ependyma is considered by many 

 anatomists as a portion of the arachnoid 



Fig. 201. 



Magnified 350 diameters. 

 Corpora amylacea, from the human ependyma. 



membrane. Corpora amylacea are often met 

 with beneath it, as is sometimes also brain- 

 sand. 



BiBL. Kolliker, Mikr. Anat. ii. 



EPHEBE, Fr.— A genus of Lichineaj 

 (Gymnocarpous Lichens), usually described 

 in an imperfect state as species of Stigonema, 

 a supposed genus of Algse. E. puhescens 

 has a hairy branched cartilaginous frond, 

 covering the surface of damp rocks with a 

 blackish green felt ; the branches are sub- 

 ulate and the plant is dioecious ; some speci- 

 mens have the branches swollen into spindle- 

 shaped receptacles, in which are imbedded 

 numerous concept acles, opening by a pore^ 

 lined with clavate thecce, each containing 

 eight uuiseptate spores ; other specimens 

 bear sphericalor subovoid,subapical j7^c/iic?m, 

 in which are immersed spermagonia, dehis- 

 cing by a pore, containing numerous linear 

 basidia {sterigmata), supporting very slender 

 oblong spermatia. The substance of the 

 branches consists of three layers; the outer- 

 most, which gives the Lichen its cartilaginous 

 consistence, is formed of thick and resisting 

 tissue ; the intermediate layer is formed of 

 large cells (gonidial), which are at first 

 rounded, then angular by compression, red- 

 dish brown or green, at first in fours, finally 

 subdividing into groups of cells, which 

 render the surface of the branches tubercular. 

 These groups in perfect examples form 

 transverse bands, separated from each other 

 by tissue of a lighter colour, in the substance 

 of the larger branches; in the young branches 

 they are piled one above another, without 



any separating tissue. The third layer is 

 the medullary, which fills up the centre of 

 the branches; it is in this that the concep- 

 tacles and spermagonia are developed. Two 

 supposed species of Stigonema, Ag. {atro- 

 virens and mammillosum), have been found 

 in fruit as perfect Ephebes, by Mr. Thwaites ; 

 it is not stated whether they are distinct 

 species. Fries speaks of E. pubescens and 

 E. mammillosum. According to Flotow, 

 forms of this Lichen have been described 

 under many names by Kiitzing and others. 

 It is the Collema pubescens of Schaerer's 

 Enumer., Cornicularia pubescens of Acharius. 



See Stigonema. 



BiBL. Bornet, Ann. des Sc. nat. 3 ser. 

 xviii. p. 155. pi. 7; Berk, and Br. Ann. Nat. 

 Hist. 2 ser. vii. p. 188 ; Von Flotow, Bot. 

 Zeit. viii. p. 73 (1850) ; Fries, Summa Veg. 

 122, A long enumeration of authors is given 

 by Bornet. 



EPHEDRA, L.— A genus of Gnetace^ 

 (Gymnospermous Flowering Plants), remark- 

 able for the jointed character of the stems, 

 the peculiar character of the wood, and 

 other points of structure. 



See GnetacevE and Wood. 



EPHEMERA, Linn.— A genus of Neu- 

 ropterous Insects, of the family Ephemeridae. 



Char. Wings four; posterior filaments 

 three ; head of larva with cornua. 



The larva and pupa are favourite micro- 

 scopic objects, for showing the dorsal vessel, 

 the circulation, branchial plates, &c. See 

 Ephemerid^. 



EPHEMERE^.— A family of inopercu- 

 late Acrocarpous (terminal-fruited) Mosses, 

 usually dwarf, csespitose or gregarious. Stem 

 almost simple. Leaves more or less oval or 

 lanceolate, slightly concave, pellucid, with or 

 without nerves. Cells of the leaves paren- 

 chymatous, lax in all parts, elongate, not 

 papillose. Capsule mostly obliquely apicu- 

 lated. 



British Genus. 



I. Ephemerum. Calyptra campanulate. 

 Inflorescence moncEcious or dioecious (anthe- 

 ridia on a very short special branch situated 

 near the base of the stem). 



EPHEMERID^ (May-flies).— A family 

 of Neuropterous Insects. 



Characterized by the minute size of the 

 antennae ; the unequal size of the anterior 

 and posterior pairs of wings ; the membra- 

 nous and almost obsolete mouth ; and the 

 elongated jointed setae at the posterior end 

 of the body. 



