BYTHOTREPHIS IN VICTORIA. 
A Carbonaceous film is all that remains of the fossil. 
It Avas ])robably a succulent marine ])lant, not unlike Fucus, 
but of a very slender form and habit.” 
The alga was obtained from Holfman's ('lay Fit, Brunswick, IMel- 
bourne, in the basal part of the Melbournian Beds of tlie Silurian 
Series (F. ('hapman). It is bedded in a pale blue pyritous sandstone, 
occurring in intermittent bands in tlie typical blue mudstone. The 
sandstone is very fine grained, but the bedding is not Avell developed, 
the irregular fracture indicating shallow water conditions. The 
Museum is indebted for its preservation to Mr. K. Eatius, one of the 
Avorkmen, who had previously found Trilobites and Brachiopods 
in the clay ])it, and aaIio took great care to gather and preserve as 
much as possible of the specimen. 
Mr. F. ('hapman has recorded other Victorian algae whicli he 
has identified with foreign s])ccies of Bythntre.jthis. I'hese are B. 
tev.uis -lames Hall, presetit in Silurian beds in the Botanical Cardens, 
South Yarra,“ B. intermedia -James Hall, in Silurian beds, South 
Yarra,^ both found in the Trenton Limestone of New York ; and 
B. divaricata Ividston, from the Tanjilian of Walhalla,'* described 
from the Wenlock of IVIalvern, England. 
The generic form B/itJiotre/dns then seems to have been dominant 
in Silurian and ()i'do\d(uan times in England, North America and 
\ictoria, and aa^c may suspect, throughout the seas of the AA^orld. 
By the apparent sini))licity of its structure it seems to liaAm been 
an elemental or generalised type. 
Hall compared it Avdth Facas, a name not so definite in his time 
as noAA^, but in the absence of any kind of fruit it is impossible to 
associate Byfhotrephis Avith any living genus, even AAuth Dictyota, 
AAdiich it resembles in form and habit and Avdiich has much simpler 
modes of re])roduction than the jnesent restricted Facas. 
It remains to me to acknoAvledge hoAv greatly 1 am indebted 
to ]\lr. F. Cha])man for the help he has given me in draAving up the 
present record. 
EXPLANATION OF PLATE XIV. 
Fig. 1 . — BythotrepJus gracilis, J. Hall sp. Frond, natural size. 
Fig. 2. — Portion of tlie same, twice natural size. 
Fig. -3. — Cell structure of tlie carbonised surface, from a collodion film. 
The arrow shows the direction of length in the frond. Magnified 104 
diameters. 
2 ll’ro(\ Uoy. Soc.,vol. xv. (X.S.), pt. I., ]90:i, p. 104, pi, xvi., f, 1. 
ti l(l('utifle(i by F. CliapiiiiUi, Nat. Mus., Coll. 
4 liec. Geol. Siirv. Yict., vol. ill., pt. 2, 1912, p. 231, pi. xxxviii , f ] 
Ry All! Iioi’it y : II. J. (Ikkfx. (-ovoniiiuMit Priiitor. Aiolboiiviie, 
[ 158 ] 
