ON SOME AUSTRALIAN TERTIARY CORALS. 185 
development has net ago - i previous ietiieliapediiilin ne wr 
bours of the eminent n naturalist Dana, whose 
on t the Pocwlavins of Wilkes’ 8 United States Exploring Expeditions 
(1vol, _ ae PR oe , 1846 ; atlas fol., 1849) ve an epoch in 
the se may be as we il to mention, for t ormation 
of aclabin shat many important extracts from this work are 
rap m Silliman’ s Asnariows Journal of Sciences. 
acaba ce This must be the case with alls jodie, and in ‘lie 
corals, where we “ae so little to go upon—so few features upon 
which to erect generic and specifie differences—it must be always 
felt. The difficulty that occurs to me is in determining the pre- 
sence or absence of organs upon whieh generic distinctions are 
made to r Thus, in the Turbinolide, we have sub-family 
distinctions built on the presence or absence of pali, and this 
describing, seaesce the characters of two or three genera (Conosmitia 
&e.), or rshow 
which our sree pare "Take, for enor the 
costal features, ms the Turbinolide we find avery peculiar strue- 
ture in five or six s There are only three cycles of septa, 
exactly like modified septa, only that there is one cycle more t 
the septa of the calice, and cons net we have a rib or septum 
on the out v 
MLUSHo ¥ 
ie: This will pena more extra traordinary if we call to mind _— 
is the doctrine with regard to the coste, and I must be 
for n making an extract from Messrs M.E. and H.’s work: (Net. 
. des Cor., vol. 1, p. 58). “The — — = gives origin to 
centripetal prolo canteen which we eal bears also in - 
most cases projections or lamine ee to the septa, which . 
develop thumeolres in a contrary dire scons and which we call 
