IV. 
CHORDARIACEiE.— Elachista. — Myrionema. 
]3i 
VI. ELACHISTA. Duly. 
Fronds parasitical, penicillate, composed of axial and peripheric filaments. Axial 
filaments dichotomously branched, cohering together into a tubercular common 
base. Peripheric filaments, simple, free, penicillate, radiating from the base, coloured, 
articulate. Fructification : pear-shaped spores attached to the axial filaments, and 
hidden within the tubercular common basis. 
Elachista fucicola , Fries.; tufts pencilled; filaments elongate, flaccid, mem- 
branaceous, attenuated upwards ; articulations once or twice as long as broad ; 
tubercle spherical. J. Ag. Sp. Alg. 1, p. 12. Harv. Phyc. Brit., t. 240. Phy- 
cophila fucorum , Kutz. Sp. Alg. p. 541. (Tab. XI. B.) 
TIab. Parasitical on the fronds of Fucus nodosus and F. vesiculosus. Narragan- 
sett Pier, Mr. Olney. Halifax, W. H. H. (v. v.) 
A common parasite on littoral fuci, forming brown or foxy -coloured pencils of 
filaments. I am acquainted only with the two American stations recorded above, 
but most probably this parasite will be found all along the shores of the Northern 
States. 
Plate XI. B. Fig. 1 . Tufts of Elachista fucicola, growing on Fucus nodosus , 
the natural size ; fig. 2, a small portion of a tuft magnified ; fig. 3, a spore with 
paranemata ; fig. 4, 5, portions of the pencilled filaments, the latter figures highly 
magnified. 
VII. MYRIONEMA. Grev. 
Fronds minute, parasitical, cushion-like, composed of axial and peripheric fila- 
ments. Axial filaments decumbent, branched, spreading as a thin expansion on 
the surface to which the parasite adheres. Peripheric filaments short, erect, simple, 
springing from the decumbent expansion, and united by interposed gelatine into 
a cushion-like frond. Spores oblong, affixed either to the erect or to the decum- 
bent filaments. 
A genus of minute parasites which annually attack the smaller red and green Algie 
in old age, and hasten their decay. The following is so common on old fronds of Ulva 
latissima and Enteromorpha compressa , both common American shore plants, that I 
s 2 
