452 CASH: FOSSIL FRUCTIFICATIONS OF YORKSHIRE COAL MEASURES. 
What is the plant to which these Calamostaclnjs fruit spikes 
should be referred, is a question which, I fear, we are not yet in a 
position to answer very definitely. That it belong to Weiss' group 
of Cidamariop.^ 1 have no doubt, further than that I am not at present 
prepared to go, except to express my opinion that it is not a true 
Caliiniitcs, and I think a comparison of the transverse section of the 
fruit-spike axis of Calamostachys with the stem of Calamifes will 
substantiate this view. On the latter (plate XXIX.) we have a 
hollow stem with a pith of ordinary looking parenchyma, whose 
elements are rounded or polygonal in shape, and are larger and have 
thinner walls towards the centre than at the periphery, surrounding 
this is a ring of wedge-shaped masses of vascular tissue, each of 
which carries at its apex a well-marked internodal canal, these 
are enclosed by a very thin Cambium zone, outside of which is a 
cortex composed of three portions, the inner, middle, and outer 
cortical layers. This arrangement is in marked contrast to that 
of the axis of the Calamostachijs fruit spikes, instead of corre- 
sponding with it in its elements as we should expect if they were 
both referable to the same plate. Besides all this we have Williamson's 
latest discovery of further examples of what he considers to be the 
true fruit of the Calamitcs (published in his 14th Memoir on the 
Organization of the Fossil Plants of the Coal Measures), in which he 
maintains that they are truly Calamitean, since " The most absolute 
of these proofs is seen in the fact that each of three of these newly 
discovered strobili had its basal peduncle attached to it ; and that 
these peduncles are ordinary Calamitean twigs of the type, to which 
our French friends have long assigned the generic name of ArthropUm, 
and which they have, until recently, regarded as a Gymnospermous 
genus. 
List of Works and Papers consulted. 
1828. Brongniart, A. " Vegetaux fossiles," Paris. 
1831-37. LiNDLEY AND HuTTON. " The Fossil Flora of Great 
Britain," 3 vols. 
1845. CoRDA, A. J. ' Beitrage zur Flora der Vorwelt." 
Prague, 1845. 
