HICK AND CASH: FOSSIL FLORA OF HALIFAX. 
371 
preserved, our knowledg-e of this part of the stem of a Calamite is 
still very imperfect. 
Recently, however, a specimen has come into our hands which 
presents a more perfect view of the transverse section of a Calamite 
than any we have previously met with. The bark is especially 
good, and we only regret that we have not an equally complete 
section in the longitudinal direction. The following description will 
convey some idea of its appearance. 
Tlie Pith (PI. XIX., p.) is somewhat elliptical in form, with a 
greater diameter of -OQlin., and a less of •084in, It is composed 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. The actual centre is wanting, the 
tissue having disappeared leaving a lozenge-shaped empty space. 
This, however is not more than O'OTin. in length by 0-04in. in 
breadth, so that a large portion of the pith is still intact. 
The Vascular Bundles (PI. 1, v.b.). Surrounding the pith are 17 
wedge-shaped masses of vascular tissue, each of which carries at 
the apex a well-marked intemodal canal. In the transverse section 
the vessels appear of a uniform size, somewhat square in shape, and 
arranged in radial rows. Two or three rows of smaller vessels 
separate the intemodal canals from the pith. The spaces between 
the bundles that constitute the primary medullary rays, are com- 
paratively broad and short, the cellular elements soon giving place 
to radial rows of what appear to be vessels quite similar to those of 
the bundles. If this be their nature, it is a warrantable inference 
that they originate in an interfascicular cambium, which uniting the 
cambium of the separate bundles, gives rise to a complete cambium 
zone. 
The Cambium Zone (PI. 1, c.) is very thin — not more than three 
or four cells thick — and has for the most part undergone some 
compression. Its cellular constituents have thin walls, but the radial 
arrangement is not so distinct as in the cambium of a Dicotyledon. 
AVhether this is the natural condition, or due to external agencies, 
we have no means of determining. 
