and Affinities of NematopJiycus Logani. 
169 
Fig. 3. 
Lave named Lave fronds which are composed of one or many 
filamentous unjointed cells. In Biphonese tLe wLole plant is 
composed of one LrancLing cell as in Bryopsis and Caulerpa, or of 
many filiform brandling cells joined together into a spongy mass, 
as in Godium and Halimeda. In tLe Dasycladese the simple or 
branched unjointed stalk gives off whorls of jointed filaments, as in 
Acetabularia. And in Valoniacese the stalk is also composed of 
many inarticulate cells united into a firm body by the small 
horizontal branching tubes, whilst the head is composed of many 
jointed filaments, as in Penicillus. Excluding the jointed fila- 
mentous growths of the latter two orders, their structure agrees 
with that of the Siphonese in being composed of one or many 
ramifying simple filamentous cells. And inasmuch as the portions 
of NematopJiycus with which we are acquainted are, as I have said, 
almost certainly portions of a stalk, we can only get a key to its 
affinities by an investigation of similar parts in existing plants. 
The articulated frond or stem of 
Halimeda is composed of a series 
of large tubes (Fig. 3), which 
give off numerous smaller and 
repeatedly branching tubes which 
pass out in a more or less hori- 
zontal direction to the exterior 
of the plant, where they cohere 
together and form a thin super- 
ficial layer of small spherical cells 
as seen from the outside. 
The stipes of Penicillus often 
attains a considerable thickness, 
yet it is wholly composed of a 
multitude of densely interwoven 
longitudinal unicellular filaments, 
which send off laterally slender 
branches that repeatedly branch 
and pass out, as in the lobes of 
Halimeda, to form the periphery 
of the stem. 
As far, then, as the presence of 
large longitudinal unicellular filaments, and of smaller more or less 
horizontal filaments are concerned, the structure of NematopJiycus 
agrees with the stems of these three orders of Chlorosperms. I 
have not been able to determine the connection of the smaller with 
the larger tubes in the fossil, as one would expect from the analogy 
with the recent forms. My friend Mr. James Smith, F.L.S., also 
made a careful examination of specimens with the view of detecting 
any relation between the two sets of tubes, but without success. I am 
further indebted to Mr. Smith for confirming my other observations 
