Barber . — The Structure of P achy theca. II. 161 
9. As regards the reproduction of Pachytheca nothing is 
known. Two suggestions have occurred: — 
(a) Possibly the branchings and swellings at the ends of 
the cortical filaments may have something to do with spore- 
formation (Fig. 9). 
(b) It is suggested by specimen 1 % that a new formation 
of a daughter sphere may take place within the body of 
the parent. 
10. The principal localities of the fossil are collected at the 
end of the paper. Pachytheca is found as low in the Silurian 
as the Denbighshire Grits, and its range extends upwards 
into the Old Red Sandstone. 
