58 
THE GEOLOGIST. 
rians, wliich resembles the preceding in the development of the 
inner walls of its corallites, but differs from them, and allies itself to 
the next by its mode of reproduction, which is exclusively calicinal. 
This gemmation, as it is called, is a very interesting and instructive 
feature. Cyatliophylhim truncatum is a good example of it. I have 
often picked up this coral in a Dudley, or Wcnlock lime-quarry, 
in which the parent — a simple, but somewhat angular shaped 
cup — has been smothered by the growth of young buds from out 
its calice. Indeed, in many specimens I have seen, these un- 
natural children have in turn borne young, and a tall turbinate 
mass of corallites, with calices mis-shapen by crowding together, 
has grown up. 
The last division of the " cup- and star-corals" includes those com- 
posite species that have a common basal plate, and grow by accre- 
tional development. Stromhodes typus is the best known. The 
star-headed terminations of its corallites cover the surface with ir- 
regular polygonal figures, the value of whose angles would puzzle old 
Euclid himself. This species has vertical internal radii, thus differing 
from its ally, 8. Murchisoni, whose inner structure is completely vesi- 
cular. Another species, 8. Phillvpsii, has elegantly shaped calices, 
having their angles gracefully lengthened ; while the perfection of 
beauty is attained by 8. dijfluens, whose surface, exhibiting no trace 
of walls dividing the corallites, is covered with the most exquisite 
septal floriations. 
Nearly alHed by form of cahce to the cup-corals are the Fungidce, 
or "mushroom-corals," an outstanding group of which one genus only 
seems to have lived in Silurian seas, Puloeocyolus it is called, i.e., 
ancient circle. P. porpita has a quoit-Uke coralliun, thirty large 
septa alternating with a like number of smaller ones, and a curved 
peduncle-foot of attachment. P, prceacutus is about the size, 
and not much thicker than a sixpence, has forty-eight uniform 
septa, and no peduncle. P. Fletcheri is about half an inch high, 
has a strongly curved peduncle, and well marked accretion- wrinkles ; 
superior height gives it advantages, you see. But P. rugosus is 
taller still, somewhat top-shaped, and has a small peduncle, oddly 
turned up. 
I have now to describe the nuUeporal corals, the second great 
