On the Fossil Genus Sporocarpon. 
BY 
R. C. McLEAN. 
With Plates VIII-X. 
S OME years ago the present writer gave a short description (1) of a group 
of fossil structures, occurring in the coal-balls of this and other 
countries, of which the true nature has long been problematical. 1 Minute 
and complex as these bodies are, they have often been misunderstood, and 
they have in consequence undergone many vicissitudes of classification since 
they were first described by Williamson (2). Although they are preserved 
in a typically vegetable manner, and constantly associated with abundant 
plant remains, it was thought proper, when the previous description above 
referred to was published, to establish the several genera as a group of 
extinct Protozoa. At the same time it was maintained that they should 
be included in the class Rhizopoda and that their affinities amongst living 
organisms were most nearly with the Radiolaria. 
Notwithstanding this allegation of their animal nature they are 
historically the property of botanists, since only botanists have written 
or interested themselves about them, and they are, moreover, constantly 
passing under the notice of fossil botanists, so that perhaps one may be 
permitted to introduce an account of them into a strictly botanical journal, 
as being, so to speak, in our own province. 
The question of affinities was fully discussed in the previous article, 
and it is needless to cover the same ground again, except to point out that 
no other explanation has offered anything like so satisfactory an exegesis 
of their structure, and that fresh observations have only tended to confirm 
the opinion previously advocated, while rendering any of the rival hypo- 
theses practically untenable. 
As fossil Rhizopoda (= Sarcodina) these organisms are remarkably 
isolated, for the only other orders in the class which have been found fossil 
are, of course, the Radiolaria themselves, and (to a much smaller extent) 
the Foraminifera ; while as an extinct group of Protozoa they are unique. 
1 The present descriptions are intended to be stipplementary to those details which were 
originally given. 
[Annals of Botany, Vol. XXXVI. No. CXLI. January, 1923.] 
