172 On the History, dec., of Nematophycus Logani. 
microscope. The ‘ lines of growth ’ would have their parallel in the 
pseudo-exogenous stems of the existing Lessonia. In connection 
with this Alga, it is a curious coincidence that Dr. Hooker remarks 
that in the Falkland Isles the ignorant observer at once takes the 
trunks of Lessonia washed up on the shore for pieces of drift- 
wood.” * 
Prof. Dickie, of Aberdeen, whose algological labours are well 
known, says, “ The plant must have been an Alga ; but unless we 
know the structure from centre to circumference, its exact place 
cannot with certainty be determined.” 
My friend Mr. Lindahl, of Lund, was so good as to submit a 
slide to Agardh, and he sends me the estimate that Agardh formed 
of it in the following words : — “ He says that it is not like the texture 
of any known species of Alga, but still it is far less like anything 
else that he knows, and that he cannot at all believe that it is 
a conifer.” 
It is unnecessary for me to add to these testimonies; I am 
satisfied to leave the decision in the hands of those who know any- 
thing of histological botany. The faithful drawings that accompany 
this paper supply sufficient data for appreciating the structure, and 
for forming a proximate estimate of the position of the fossil. This 
is not a matter for the mere geologist. 
The following short exhibition of the systematic position of 
the fossil, with the diagnosis of the genus, and the synonymy, will 
fittingly close the paper. 
ALGLE. 
Class. — Chlokosperme^:. 
Inter Siphonearum, Dasycladearum et Valoniacearuni Ordines. 
Nematophycus. Gen. nov. Stem wholly composed of innume- 
rable longitudinal unjointed cellular filaments woven together by a 
multitude of small sub-horizontal cellular inarticulate tubes, so as 
to form in the living plant a compact spongy mass. 
Sp. — N. Logani, Carr. 
Syn. — Prototaxites Logani, Dawson, ‘ Quart. Journ. Geol. Soc.,’ 
vol. xv. (1859), p. 481, Fig. 4. ‘ Pre-carboniferous Plants’ (1871), 
p. 16, Plate II. 
Nematoxylon crassum, Dawson, ‘ Quart. Journ. Geol. Soc.,’ 
vol. xix., p. 466, Plate XIX., Fig. 24. ‘ Pre-carboniferous Plants ’ 
(1871), p. 20, Plate XI., Fig. 137. 
* ‘ Quart. Journ. Microsc. Science.’ New Series. Vol. xi., pp. 319, 320. 
