On the Occurrence of Arthrostigma gracile. 103 
These are like Cyclostigma markings; but in this specimen 
they are certainly the markings on the inner surface of the 
false bark of these plants. The spines are, I believe, the 
persistent bases of leaves, not the leaves themselves, though 
that is possible. But I see, I think, indications of their 
being bases from which the leaves have disappeared. The 
leaf is not clean-cut on the upper margin, but has something 
like a cicatrix scar.” 
Mr Carruthers concludes his remarks by saying: “ As to 
their name, it is probably the larger stem of a plant like 
Dawson’s Psilophyton princeps, with which it agrees in 
structure, etc. No doubt his Arthrostigma and Cyclostigma 
are the same things; but we yet want light as to the true 
nature of these Devonian Lycopods.” ! 
The authors of the paper then state: “The preceding 
facts comprise all the information we at present possess 
bearing on these interesting fragments. Beyond the probable 
dichotomous method of branching, we are unacquainted with 
any of the broader characters ; neither do we know anything 
of the fructification. 
“The plentiful manner in which the matrix is traversed, 
gives rise to the hope that the discovery of more perfect 
specimens is only a matter of time and careful search. 
Under these circumstances, we content ourselves with 
appending a short provisional description, under the name of 
Psilophyton (?) sp., in accordance with the suggestion of Mr 
Carruthers, as given above.” 
PSILOPHYTON (?) sp. 
“Stems branching dichotomously, and covered with spirally 
oblique lines of short, rigid, pointed and slightly curved thorn- 
or spine-like projections, the persistent bases of the leaves, 
or perhaps the leaves themselves. Axis composed of a 
slender column of vascular tissue, surrounded % By a cylinder 
of cellular tissue.” 
1 This description refers to characters which none of the Perthshire 
specimens which I have seen shows. 
