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Two of these, as has l)een seen, have necessitated the erection of new 
genera ; and it is not inipossil)le that in the future, when ])etter specimens 
than those submitted to me have been obtained, that it may be decided 
to propose new genera for the reception of the other two forms. 
The first {Archceocijathus Clarkei) seems to take in Australia the place 
occupied in certain Devonian beds in Europe, and more particularly in 
Belgium, by ReceptacuUtes Neptimi, Defrance, which, as well as it, belongs 
to the order of the Spongida. This is the first time the genus Niso has been 
recorded from Palscozoic formations, and we have to go right up to the 
Tertiary before again finding traces of it ; hoAvever, my learned and excellent 
friend, M. Nyst, Avithout doubt one of the best Conchologists of the day, whom 
I consulted on the matter, considers he is justified in agreeing with me that 
there is not sufficient difference betAveen the general characters of the Devonian 
species and the Tertiary to justify us in not considering them generically 
identical. 
The existence of this genus, together Avith that of the genus Mitchellia, 
Avhich I would have readily referred to the family Auriculidse, if it had not 
been found associated Avith marine shells, is the only striking anomaly to 
record in connection Avith the composition of the Devonian Eauna of Australia, 
as compared Avith that of Europe. It is certainly not sufficient to prevent 
them both being considered as contemporary, and produced under circum- 
stances, if not quite the same, at any rate very analogous. 
Q 
