350 
PROFESSOR W. WILLIAMSON ON THE ORGANIZATION 
sporangium lias a diameter of about ‘005. That this has been a strobilus of some 
kind is unquestionable, and it is equally obvious that it is very distinct from any fruit 
the internal ouanization of which has hitherto been described. It is from the Oldham 
O 
deposits. It has a Lypocodiaceous look about it, but until we learn more respecting 
it I would apply to it the provisional name of Volhnannia (?) parvulct. 
Ferns, 
Two new structures, apparently belonging to this family, have been met with since I 
wrote my sixth memoir. One of these is a transverse section (fig. 79) of a petiole 
found in one of the Oldham nodules, by Mr. Isaac Earnshaw, to whom I have been 
indebted for the loan of several instructive spec im ens from that locality. It obviously 
belongs to the same type as the Chorionopteris gleiche of Cord a. * In Corda’s specimen, 
the walls of the vessels of the vascular bundles are very regularly reticulated. Though 
Mr. Earnshaw’s plant is very opaque, I detect distinct evidences that its vessels 
were of the same reticulate character. Within the doubly incurved vascular bundle is 
a mass of very small cells, whilst the cortical layer is composed of larger ones. 
Since I can detect no difference between this Oldham specimen and Corda’s, I venture 
to attach his specific name to it and designate it, in accordance with my previously 
adopted plan, Rachiopteris gleiclie. Its mean diameter is about 'll. 
Amongst the new objects with which the Halifax beds have rewarded the researches 
of Messrs. Binns and Spencer, are some stems or roots which for the present I have 
located in the provisional genus Rachiopteris, though I am far from certain that the 
objects are time ferns. Fig. 80 represents the transverse section of an axis which 
appears to be of the maximum size of these objects so far as the specimens hitherto 
discovered enable us to judge. Its diameter is about '066. In its centre is a 
cylindrical bundle, about '025 in diameter, composed of barred vessels. The central 
ones are very small ; the peripheral ones, on the other hand, very much larger, having 
a mean diameter of '004. This vascular bundle is surrounded by a thick ring of very 
minute cells, a ; the outer margin of this zone, which appears to form a sort of bundle 
sheath, is rather sharply defined. It is enclosed in a cortical layer of larger cells, h, 
from '008 to '016 in thickness, the cells of which exhibit a little tendency to arrange 
themselves in irregular concentric circles, after the fashion of those composing the 
root-stems of P silo turn triquetrum. Figs. 81, 82 and 83 are three successively 
smaller axes. In each of these the central vascular bundle consists of but few 
vessels of various sizes and not disposed in any uniform manner ; the central vessel 
of fig. 8 1 and the three central ones of fig. 8 2 being not only the largest in the bundle 
but actually larger than those occupying its centre in fig. 80. Fig. 83 is further 
enlarged to 140 diameters in fig. 85. The latter figure exhibits the vascular bundle 
composed of very small vessels. The line of demarcation between the exterior of the 
* Flora der Yorwelt, taf. liv., fig. 8. 
