Barber . — The Struclrue of P achy thee a. IL 157 
may have caused a funnel-shaped divergence of the filaments 
from one point of the cortex outwards. I have noted several 
such disturbances and corresponding divergences in radial 
sections ; and it is perfectly reasonable to suppose that a 
tangential view of such an arrangement might give the star- 
like appearance described. On the other hand, the idea which 
most prominently asserts itself is that we have to do with 
a mode of reproduction by the endogenous formation of new 
individuals. 
Another peculiarity of the same specimen is worthy of note. 
The part usually occupied by the medulla consists, in this 
section, of a number of polygonal areas of great regularity. 
As far as can be judged, this peculiar formation is brought 
about by the regular arrangement of the filaments in meshes. 
The Rivularia-like body occupies the centre of the organism, 
and the peripheral portion, as usual, consists of radiating 
filaments. 
Another specimen, on Slide 13, shows, on one side, a large 
number of more or less parallel, short filament-segments, 
which pass without interruption far into the medulla. At 
other parts of the section, the zone of oval bodies, entirely 
absent at this point of invasion, is found separating medulla 
and cortex as usual. 
PRINCIPAL LOCALITIES OF THE FOSSIL. 
Various places are mentioned in Murchison’s Siluria 1 where 
Pachytheca is to be found. Among these, it is found in the 
Bone-bed at Ludlow and Hagley Park near Hereford, and in 
the Old Red Sandstone of Clun Forest. Specimens from the 
latter locality are figured under the name of Bufonites (see 
Plate XXXV, Fig. 30). 
Almost every place that I have visited, where the transi- 
tion beds between the Old Red Sandstone and the Silurian 
crop out, has furnished me with traces of the fossil. I may 
specially mention the Downton Sandstone near Onibury, 
Norton and Forge Bridge in South Shropshire, and the Perton 
1 1. c. pp. 135, 138, 140, &c. 
M 
