EQUISETACEJE. 



C 301 ] 



ERIODERMA. 



at their free ends. While the spore remains 

 in the sporange, these fibres are rolled round 

 the spore ; but when the spores are dis- 

 charged, the coiled fibres uncurl (fig. 205), 

 and assist in scattering the spores, their 

 elasticity causing them to spring out. 



The Equiseta possess only this one kind 

 of spore ; and the germination is analogous 

 to that of the Ferns, in which likewise only- 

 one kind of spore exists. The membrane 

 of the spore pushes out a pouch-like pro- 

 cess, which after a time becomes cut off 

 by a septum ; the end-cell grows on and 

 multiplies in both directions, until a lobu- 

 lated prothallium is produced ; on this arise 

 archeyonia and antheridia, in distinct indi- 

 viduals, the archegonial prothallia being 

 larger than the antheridial, and resembling 

 in all essential respects those produced on 

 the corresponding structure in the FEBNS. 

 The antheridia are formed on the ends or 

 the margins of the male prothallia. The 

 spermatozoids are larger than those of other 

 Cryptogamia ; they have 2 or 3 coils, the 

 posterior thickened portion being furnished 

 with an appendage, supposed to consist of 

 an undulating membrane. 



After the fertilization of an archegonium, 

 the germ-cell contained in it becomes deve- 

 loped as an embryo, and a new Equisetum- 

 stem of the ordinary structure springs up 

 (fig. 206), forming a creeping rhizome with 



Fig. 206. 



Equisetum arvense. 



Young stem arising from a prothallium. 

 Magnified 15 diameters. 



upright fistular shafts, resembling the parent 

 plant from which the spores were derived. 

 The family Equisetaceae is represented 

 in existing vegetation by a single genus, 



containing only herbaceous plants. The 

 Equisetaceee of former ages were far more 

 important as regards size. 



BIBL. Francis's British Ferns, 5th ed. 

 1855 ; Thuret, Ann. So. Nat. 3 ser. xi. 5 ; 

 Milde, Bot. Zeit. viii. 448, and x. 537, 

 Linncea, xxiii. 545 ; Hofmeister, Vergleich. 

 Unters. 1851, Verh. k. Sachs. Akad. d. Wiss. 

 iv. 123; Bischoff, Erypt. Geivachse, Heft 1, 

 27, pis. 3, 4, 5, Botan. Zeit. xi. 97 ; Prings- 

 heim, Bot. Zeit. xi. 241; Sanio, Bot. Zeit. 

 xiv. 177, xv. 657 ; Milde, Nova Acta, 1867, 

 xxxv. ; Nageli and Leitgeb, A%.ife^.iv.lS67; 

 Janczewskry, Bot. Zeit. 1872, 420 ; Tieghem, 

 Ann. Sc. Nat. 5 ser. xiii. ; Sachs, Bot. 389. 



EREBONE'MA, Rom. A supposed ge- 

 nus of Kiitzing's family Leptoiniteae. Some 

 imperfect filamentous organism, probably 

 belonging to a Fungus. 



BIBL. Romer, Deutschl.Alg. 70; Kiitzing, 

 Sp. Alff. 157. 



EREM^'US, Koch. A genus of Ori- 

 batidae (Acarina). 



Char. Cephalothorax without lamellas ; 

 tarsi with heterodactyl claws. Allied to 

 Hoplophora. (Murray, EC. Ent. 222, fig.) 



ERE'MOSPILERA. See CHLOBO- 



SPHJERA. 



ERE'TES, Wemeck. A genus of Infu- 

 soria, of the family Cryptomonadina. 



Char. Those of Phacelomonas with a 

 carapace. 



One species : the spores of an Alga ? 



BIBL. Werneck. Ber. Berl Ak. 1844, 

 377. 



ERGOT and ERGOT^E'TIA. See CLA- 



VTCEPS. 



ERIN'EUM, Pers. A supposed genus 

 of Fungi, really consisting of abnormal de- 

 velopments of the cells of the epidermis of 

 the trees upon which they are supposed to 

 be parasitic; or galls, produced by the action 

 of Phytoptidae. They occur chiefly upon 

 the Anientacese, Aceraceae, and RosaceaB 

 (Apple-trees, Plum-trees. &c.). 



See TAPHRINA. 



BIBL. Fries, Syst. Mycol iii. 521 ; Berke- 

 ley, Lindleifs Veg. Kingdom, art. Funyaks ; 

 Murray, EC. Entom. 331. 



ERIODER'MA, Fee. A genus of tro- 

 pical Lichens, tribe Lecanorei, externally 

 resembling the Peltigerae ; consisting of a 

 green membranaceous thallus, spreading 

 from the centre, hairy above, and with 

 woolly anastomosing nerves beneath. Apo- 

 thecia marginal, with hispid hairs on the 

 margin underneath. 



BIBL. Fee, Crypt. 145, pi. 34. fig. 2. 



