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XVIII. On the Organization of the Fossil Plants of the Coal-measures . — Parti. Cata- 
mites. Py W. C. Williamson, F.B.S., Professor of Natural History in Owens College , 
Manchester. 
Received November 11, 1870, — Read January 26, 1871. 
A few preliminary tvords may be necessary to prevent misunderstanding respecting the claims and objects 
of the following memoir. When I entered upon the investigation of which it records the results, I found, in 
the writings of various British and foreign authors, a copious Calamitean literature ; but the voidest discrepancies 
prevailed amongst them both as to facts and to inductions. I therefore determined to pursue the study of this 
group of fossils as if de novo, to record the facts which I observed, and to draw from those facts alone such 
inferences as seemed legitimate, both facts and inferences being in a certain sense, and so far as was possible 
under the circumstances, new and original. But it necessarily follows that some of these facts and inferences 
are not absolutely new, though many of them, I think, will be found to be additions to our knowledge of the 
subject; whilst others, though not neiv, have presented themselves to me in a light different to that in which 
they have been regarded by my able predecessors in the study. Such being the object of the memoir, I have not 
deemed it desirable to include in it a record of all the observations made by preceding writers. As a rule I 
have only referred to them when the discussion of some moot point rendered such a reference necessary. The 
fundamental aim of the memoir is to demonstrate the unity of type existing amongst the British Catamites. 
Brongniart, Dawson, and other ivriters believe that there exist amongst these plants two types of structure, the 
one Cryptogamic and Equisetacean, the other Exogenous and Gymnospermous ; on the other hand, Schimper 
and Carruthers regard the ivhole as Eguisetaceous, affording an example of the diversity of opinion on funda- 
mental points to ivhich I have already referred. Of course, before arriving at their conclusions, Brongniart, 
and those who adopt his views, had fully apprehended the exogenous structure of the ivoody zone of the Gala- 
mite, ivhich is further illustrated in this memoir. The separation of each internode into vertical radiating 
plates of vascular and cellular tissues, arranged alternately , was familiar to Brongniart, Unger, and other 
early observers. Cotta regarded the cellular tracts (my primary medullary rays) as medullary rays ; but this 
interpretation was rejected by Unger, and the same divergence of view on this point has recurred amongst sub- 
sequent writers. Unger also noticed what I have designated secondary medullary rays, but at a much more 
recent date Mr. Carruthers disputed their existence. In their ‘ Fossil Flora of Great Britain,'’ Bindley and 
Milton gave very correct illustrations of the position of the roots of Catamites relatively to the stem ; and yet 
for years afterwards some of their figures reappeared in geological text-books in an inverted position, the roots 
doing duty as leaves ; so far was even this elementary point from being settled. The true nature of the common 
sandstone form of Catamites, viz. that they are inorganic casts of the interior of the woody cylinder from which 
the pith has been removed, has been alike recognized by Germar, Corda, and Dawes ; but they referred the dis- 
appearance of the cellular tissues of the pith to inorganic decay which took place subsequently to the death of 
the plant. It appears to me that the condition in ivhich we find these cellular tissues affords no countenance to 
this conclusion. They are as perfectly preserved, when present, as any of the other tissues of the plant. Tlieir 
inner surface, nearest the fistular cavity , presents no appearance of death and decay, but of rupture and adsorp- 
tion, ivhich I conclude has occurred during life , — a different hypothesis from that adopted by my predecessors, 
and for which my reasons will be assigned in the memoir. The labours of Mr. Binney are referred to in the 
text. Me figured the longitudinal internodal canals, but was disposed to believe that they had merely formed 
passages for vessels. Me gave, however, excellent figures of the ivoody wedges, the primary medullary rays, and 
the cellular medulla, with its nodal septa or diaphragms. 
The above may be received as examples of the many discordant views entertained by the various authors who 
have written upon the subject of Catamites, and may probably be regarded as a justification of the method which 
I have deemed it best to adopt in this memoir . — Note added July 12, 1871. 
Notwithstanding the large amount of attention which has recently been paid to the 
MDCCCLXXI. 3 U 
