A mongst the collection of corals which was submitted to me for examination from the Tertiary beds of Cape Otway in Victoria, were some specimens of Isidinæ. My memoir on the Fossil Corals of the Australian Tertiary Deposits, which was published in the Quarterly Journal of the Geological Society, vol. xxvi. 1870, p. 284, did not allude to these Alcyonaria. Now, however, it becomes necessary to examine and describe them; for there are Tertiary beds in New Zealand which contain somewhat similar organic remains (Quart. Journ. Geol. Soc. vol. xxix. p. 375). The Cape-Otway Tertiaries were described in the above-mentioned communication from the writings of Messrs. Daintree and Wilkinson, of the Geological Survey of Victoria; and I ventured to correlate them with particular Tertiary deposits elsewhere in Australia. Amongst the most interesting of the strata of the Cape-Otway section was that called No. 3, or the Upper Coralline bed. It contained, besides Amphihelia incrustans (nobis) and Balanophyllia Selwyni (nobis), the specimens about to be noticed. Being the equivalent of the Polyzoan limestone of Wood, which is of Mount-Gambier age, it is a deep-sea deposit, and covers an important series of shallower-water deposits. It is younger than they are, and forms the Upper Miocene of Daintree, the Crag of Wood, and my Upper Cainozoic stage. The specimens may be divided into three groups, which have a specific significance. In one the Isidian characters are well shown, and the furrows on the calcareous bodies are well developed; in the second the bodies are