Page:Quarterly Journal of the Geological Society of London, vol. 32.djvu/282

206 believed it to be the Saprolegnia ferax of Kützing. He did not examine the corals; but after satisfying himself about the occurrence of the parasite in recent species, he examined some fossil shells, and detected it (amongst others) in Leptæna lævis from the Devonian.

Thus these investigations showed that there were parasitic vegetable growths in modern corals and in many shells even as old as the Devonian, and that they either were confervas or fungi.

During the course of some investigations into the minute structures of Tertiary corals, I was greatly puzzled by the omnipresence of a system of branching canals ending in culs-de-sac and having dark borders and a refractive central area. In one instance (in a Thamnastræa from Tasmania) the tubes frequently merged into an irregular dark mass, and resembled the tubuli of bone (Haversian canals) passing into lacunæ; and as they surrounded in a circular series a radiating mass of closely approximated normal spicula, the resemblance to a low class of osseous tissue was extraordinary. These canals had their length, direction, and frequency evidently in relation with the situation and regularity of disposition of the denser and normal coral structures: where the spicula were closely united laterally, their extremities radiating from a common centre, the tubes did not pass into, but surrounded the mass; and when these nodules of normal tissues were in long series the tubes ran down by their sides. Hence sections cut across the calices and septa did not exhibit many tubes, but numerous dot-like markings, which were their cut ends; on the other hand, sections longitudinal to the septa and costae presented long lines of tubes with ramifications and swellings. The resemblance in shape and size of these tubes to Quekett and Wedl's figures led to the belief that even this hard coral had not been without its parasite, and incited me to follow up the subject in living, recently dead, and other fossil species.

The results of my work on the recent forms, as they enter especially into questions foreign to those considered by this Society, are about to be presented to the Royal Society; but I thought that a notice of the occurrence of these interesting parasites in such old forms as Goniophyllum and Calceola would be of interest.

I chose this species of coral and Calceola because their hard parts admit of thin and wide sections, and also because I was working upon them in conjunction with Mr. H. Woodward, F.R.S., in investigating the question of the Rugosa operculata of Lindstrom. But I have examined others also, with different degrees of success. In the specimens which Mr. H. Woodward had had cut, the fossilization had been very perfect, and much of the calcite had been replaced by crystalline carbonate of lime. The calicular fossa and the cavities,