China seas ; and the last is closely allied to such forms as the recent F. Stokesi and F. crassum ; but it has a fair specific distinction in the development of its septal cycles. Moreover F. Victorioe has the peculiar arrangement of the septo-costal structures mentioned in treating of the Sphenotrochi.
Placotrochi are Flabella with an essential and lamellar columella ; and there are species mimetic of the divisions of the genus Flabellum. There are two recent species. One, P. Candeanus (China), has a pedicellate base, and is closely allied to Placotrochus elongatus from the Australian Tertiaries ; and the other, P. loevis, is truncate, and is not represented in the fossil state. Placotrochus deltoideus is a fine species, and is very characteristic of the Australian Tertiaries.
The genus is not represented in any European formation ; but it has four species in the Miocene of Jamaica and San Domingo. It has not been distinguished, as yet, amongst the results of the dredgings off Florida and Havanna. The "West-Indian species are very distinct from the Australian, and have only a generic affinity with the Chinese recent forms.
The interesting characters of Paloeoseris Woodsi have already been noticed. The genus is allied to Turbinoseris, Duncan, from the Lower Greensand, but it has no tertiary or recent congeners.
Gycloseris tenuis is closely allied to Fungia tenuis, Dana, which is probably a Cycloseris. The thin Cycloserides are well-known fossils in the nummulitic rocks of the S. of France ; and there is one species in the Cenomanian. The recent species are from the Philippines and China.
Amphihelia incrustans is closely allied to A. venusta of the Australian coast. The dwarfed and incrusting nature of the coral, and its excessively rare calices and great amount of intercalicular tissue, covered with costae, distinguish the fossil form from all the others of the genus. The Amphihelioe; range from the Miocene of Sicily to the recent deposits in the deep sea of the N.E. Atlantic, where the earliest species still exists. Recent investigations into the affinities of the Oculinidae, which are not yet finished, lead me to expect that this Australian fossil form is most closely allied to some from the Atlantic.
The most interesting of the corals from the Cainozoic deposits of South Australia are the Conosmilioe. It is a genus perfectly Australian in its abnormalities. A simple coral with a pellicular epitheca, having a beautiful herring-bone ornamentation, with an essential, twisted, " serialaire " columella with endothecal dissepiments, and with plain septa, which have the hexameral arrangement in some and the octomeral in others, is a form containing the elements of several classificatory series. The irregular septal arrangement amongst the closely allied species maybe considered to depend upon atavism. Such octomeral cyclical arrangements occurred in some genera in the Lower-Greensand period and during the Oolites. Some of the Liassic Montlivaltioe clearly reflected this rugose peculiarity; and M. Ruperti, Duncan, had a quaternary cyclical arrangement. It is remarkable that the septo-costal peculiarity already mentioned as occurring in the Australian Flabellum Victorioe and in the two species of Sphenotro-
