74 
UPPER CAMBRIAN. 

Case and 
Column of 
Go Paleopora, p. 16. 

Pl. 1 ©, fig. 4. 
Go Paleopora, p. 17. 
Go p. 26. 
Go Cup- Corals. 

Reference to McCoy’s 
Drawers, /Synopsis: and Figures of Genera. 

See figure, p. 75. 

Names and References; Observations, &c. 
Numbers and Localities. 

Heliolites megastoma, McCoy (Si- 
luria, 1867, p. 188, Foss. 30, fig. 7). 
Heliolites subtilis, McCoy. Narrow 
branches, very small cells. 
Halysites catenulatus, Linn. (chain- 
coral). This long-lived and wide- 
ly spread coral ranges throughout 
all the Upper Cambrian and the 
Silurian formations. It is most 
abundant in limestone, but has 
no sort of antipathy to slate, shale, 
sand, or fine grit. It must have 
inhabited various depths of water. 
PETRAIA.—Munster and Phillips. 
(Turbinolopsis of Lonsdale.) 
One of the commonest and simplest 
of all the Cambrian or Silurian 
cup-corals. The calyx is so deep, 
and so strongly ribbed by the 
toothed lamelle, that the conical 
matrix left in this part (frequently 
all we have preserved), shews all 
the characters necessary for dis- 
tinguishing the many varieties, 
or species, as they are supposed 
to be. The changes from the 
young to the adult state are not 
yet sufficiently known, to pre- 
vent us from multiplying species 
on the characters drawn from the 
lamellae. The base of the cup, 
a solid mass of twisted lamelle, 
or tabulz, is short or long, large 
or minute, in proportion to the 
cup, in the various species. To 
Prof. Phillips and Prof. McCoy 
we are chiefly indebted for de- 
scriptions of the species. 
Upper Bala proper. 



Llandovery Group. 

b. 188, Mathyrafal. 
a. 200*, Dalquorrhan, 
Mullock, Girvan. 
b. 189, Mathyrafal; 
b. 190, Goleugoed. 

