See. MELANOSPERMEiE. ( 139 ) Fam. CHOIIDAUIK.E. 



MYRIONEMA LECHLANCHERII.— G^rev. 



Gen. Char. — Fronds formed of two strata of articulated filaments: 1, forming a thin 

 stratum, creeping and cohering ; 2, erect, simple. Fructification, consisting of 

 obovate spores, attached either to the erect or creeping filaments. Name from 

 fivpios, "a myriad," and vrina, "a thread," in allusion to the multitude of 

 minute filaments of which the plants are composed. 



Mtrionema Lechlancheyii. — Patches determinate, roundish, filaments 

 dense towards the middle, few towards the edges ; spores on long 

 pedicels, attached to the creeping filaments. 



Mtrionema LechlancTierii. — Harv. P. B. plate 41 a. ; Earv. Man. p. 51 ; Harv. 

 Syn. p. 47; Atlas, plate 16, fig. 69; /. G. Agardh, Sp. Gen. Alg. 

 vol. i. p. 48. 



Rivitlaria Lechlancherii, Chauv. — See Lenorm. in Lift. 



Hab. — On decaying fronds of Bhodymenia palmata. Not uncommon. Annual. 

 Autumn. 



Geogr. Dist. — Shores of Europe. 



Description. — Patches at first minute, flat, spreading in the form of 

 a thin stratum of creeping filaments, with few erect filaments, which at 

 length become numerous, closely compacted, forming a slightly convex 

 button, surrounded with a thin flat margin; filaments cylindrical, 

 scarcely clavate ; the articulations about as long as broad, slightly 

 contracted at the dissepiments. Spores obovate, attached to the creep- 

 ing filaments, or rather terminal on abbreviated filaments, from one-third 

 to one-half as long as the primary ones. More frequently, however, the 

 filaments are converted into fusiform bodies, which may be abortive 

 spores, or in some other way connected with the fractification. Sub- 

 stance subcartilaginous. Colour, greenish olive, brownish when old. 



This cm-ious and minute parasite is rather frequent on the fronds of 

 the common dulse, as they pass into decay dm-ing the autumn, and are 

 so minute that they are scarcely observable to the naked eye, except 

 by the discoloration ; looking, as Professor Harvey remarks, more like 

 incipient decay than a distinct organism, their curious structure only 

 becoming apparent when placed under the microscope. 



