186 ON SOME AUSTRALIAN TERTIARY CORALS. 
coste. These parts are gle of the same Dist cnanGcI as 
the septa, a are in fact only the exterior continuation of 
them, which is easily seen “es I the Turbinolide, Phytlan- 
gia americana, Heliastrea Forskaliana, and many other corals 
simple and compound. All that has pate said of the septa, os 
fore, is true of the costa as to their relative positions and modes 
multiplication. 
| Micrabacia, the cost alternate with the external edge of ne 
pta as if the tw ge of these were 
gr neared from one another to unite with the external 
r : : 
Now 
form an apisdarinem to this rule. The costz do not co 
with the septa, but exceed them in number. If this ook Sa 
in one genus alone, as it does in Turbinolide, we might not wonder 
so much, but it appears in remote genera. Thus we have this 
sulcatus, and, as I shall show in a species now to be described, it 
oceurs in another species, and in a Ceratotrochus. ore ey case it 
seems as if the coral animal had its support on the e 
eaieies of the cone is intimately connected with sebties of the 
animal, and their number y with those appendages. 
It is not known, or bas it I believe “nee studied, what relation 
their while to ascertain the siakcuiien: structure of Conocyathus 
us, which is so common. at the mouth of the harbour. 
I cannot however help raising the que ara as to the mport- 
ance of the costx in the matter of classificati It seems to me 
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act aang or four different genera. Distinctions. agence 
‘on the columella and pali are most unsatisfactory: in very many 
or with pali attached to the se septa. I ma ale these remiurks wit th 
the utmost diffidence, and not a ttempting to-cause any confusion 
by. ousting new divisions, only let it be borne in mind that they 
Sm Mee Serta pieces 
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Bes a ae 
