Oeological Society. 167 



saurs and the lower Ganocephalous reptiles of the Carboniferous 

 series, in which, however, the vertebral centra are more widely 

 perforated. 



January 19, 1876. — John Evans, Esq., F.R.S., President, 

 in the Chair. 



" On some Unicellular Algae parasitic within Silurian and Ter- 

 tiary Corals, with a notice of their presence in Caheola sanda- 

 lina and other fossils." By Prof. P. Martin Duncan, F.R.S., 

 V.P.G.S., &c. 



Aft^r noticing the works of Quekett, Rose, Wedl, and KoUiker, 



which refer to the existence of minute parasitic borings in recent 



corals, recent shells, and a few fossil moUusca, the author describes 



the appearance presented by a great system of branching canals 



about 0-003 millim. in diameter, in a Thamnastraean from the 



Lower Cainozoic of Tasmania. He then proceeds to examine the 



corresponding tubes in GoniophyUum pyramidaJe from the Upper 



Silurian formation. In sections of that Coral one set of tubes runs 



far into the hard structure; these are straight, cylindrical, and contain 



the remains of vegetable matter. Neither these tubes, nor any 



others of the same parasite, have a proper wall ; they are simply 



excavations, the filiform alga replacing the organic and calcareous 



matter abstracted. In some places the dark carbonaceous matter is 



absent, and the lumen of the tube is distinguishable by the ready 



passage of transmitted light. Other tubes run parallel to the wall, 



and enter by openings not larger than their common calibre. But 



there are others which have a larger diameter, and in which the 



cytioplasm appears to have collected in masses resembling conidia ; 



and where fossilization has destroyed much of the continuity of a 



tube a series of dark and more or less spherical bodies may be seen. 



in some places, especially in the spaces between the minute curved 



dissepiments and tabulae, hosts of globular spores, with or without 



tubes emanating from them, may be seen. In Calceola snmlalina 



corresponding structures exist sometimes, and the method of entry 



of the parasite can be examined. The author gave two instances, 



one of which was seen in section. A decided flask-shaped cavity 



existed in the wall of the shell, opening outwards and rounded and 



closed inwards. It was crowded with gloVmlar spores (oospores); 



and these, where near the sides, had penetrati'd the hard shell, and 



thus gave a rugged and hairy appearance to the outline of the 



flask-shaped cavity. After noticing minute structures in a Bra- 



chiopod included in a Silurian Coral, and in a Lower Silurian Fora- 



minifer, the author asserted, from the results of his late researches 



upon the algae parasitic in Corals out of his own aquarium, 



that the fossil and recent forms are analogous in shape, size, and 



distribution. He considers that tlie old parasite resembles Sapro- 



leynia ferox in its habit ; and as he considers that Empusiua, Sa- 



prolffpiia, and Achhja (members of the Protista) are the same 



