66 
PROFESSOR W. C. WILLIAMSON ON THE ORGANIZATION 
mostachys. I have carefully investigated the relations which the fertile stems of the 
j Equiseta hear to axes of their terminal frnit-spikes, and I find that their respective struc- 
tures are typically identical. The transition from the stem to the fruit-axis produces no 
structural changes save such as are of the most trivial kind ; the general type remains 
unaltered and continuous. But to plant Calamostachys Binneyana upon the top of a 
Calamite would he as abnormal as to surmount the stem of an Equisetum with the 
strobilus of a Lycopod. 
Whilst expressing my conviction that Calamostachys is allied to the Asterophyllitean 
plants, I cannot as yet correlate it with any particular stem. I have no evidence indi- 
cating that it belonged to any of those described in the preceding pages, and suspect 
that the plant of which it is the fruit has yet to be discovered. Diligent search must 
continue to be made in the narrow vertical zone of beds within which the specimens 
occur, until some absolutely demonstrative facts are obtained removing the obscurity 
which still invests this very remarkable and interesting fruit. 
I have already referred briefly to one or two examples of fruiting axes of Aster oyliyllites 
and S'pheno'pliyllum in which circular scars, arranged in verticils at the nodes, marked 
the points from whence strobili had been detached. Plate VII. fig. 44 represents a similar 
stem, which I found amongst Captain Aitken’s Brooksbottom specimens. The scars (r) 
appear as if they were located below the node ; but this appearance has, I think, merely 
arisen from the circumstance that the strobili were detached before the plant was enclosed 
in the shale, thus allowing the bases of the bracts to be compressed against the stem; 
the carbonaceous matter having subsequently become detached revealed the cicatrices in 
question*. Each cicatrix is nearly oval, but slightly narrower at its lower than at its 
upper extremity, and with a distinct central depression marking the position of a vascular 
bundle. There appears to me to be a close resemblance between this specimen and the 
plant figured by Lind ley and Hutton under the name of Catamites verticillatus, but 
respecting which I have already expressed my conviction that it had no affinity whatever 
with the genus Catamites f . The stem last mentioned appears to be the same as that 
figured by Geinitz J under the name of Equisetites infundibuliformis. It becomes an 
interesting question whether this plant will not prove to be an arborescent stem of an 
Aster ophyllites or Sphenophyllum ; if so, are the characteristic scars large because they 
bore large strobili, or have they become larger through the expansion of the bark 
subsequently to the shedding of the strobili, and consequent upon the exogenous enlarge- 
ment of the vascular portion of the stem 'l Each of the large oval cicatrices of this 
plant has a central impression more or less regularly defined, indicating the former 
passage of a central vascular axis at this point, such as is seen in each of the scars of 
Plate VII. fig. 44. In some instances they probably indicate the position of branches. 
Plate VII. fig. 45 represents a fine example of Catamites verticillatus in the Museum 
* It is possible that the young buds may have burst through the slightly confluent bases of the leaves, as 
the rootlets and branches of Equiseta do through their nodal sheaths. 
t Phil. Trans. 1871, p. 507. J Die Steinkohlen-Eormation in Sachsen, tab. x. figs. 4, 5. 
