268 Royal Society : — • 



PEOCEEDINGS OF LEARNED SOCIETIES. 



ROYAL SOCIETY. 



May 11, 1876.— Dr. Giinther, M.A., Yice-President, in the Chair. 



" On some Thallophytes parasitic within recent Madreporaria." 

 By P. M. DTOCAJf, M.B., F.R.S., Pres. Geol. Soc. 



After noticing the works of Quekett, J. P. Rose, Wedl, and 

 Kcilliker on the filament-shaped parasites within recent and fossil 

 molluscan shells and fish-scales, and his own researches into and 

 descriptions of corresponding growths in Madreporaria from the 

 Silurian and Tertiary rocks, the author proceeds to explain the 

 method of investigation employed in the examination of recent 

 corals. The range of the parasites is then stated to be, in corals 

 from the littoral zone down to 1095 fathoms, and from Davis 

 Straits to the tropical coral seas, and their lowest known tempera- 

 ture habitat is that of 31°%5 Fahr. 



A List of species examined is giA en, and then the long slender 

 canals with their included filamentous organisms are described. 

 Then the method of entry of the growth is stated, and its relation 

 to the organic basis of the coral sclerenchyma is explained. The 

 reproduction by conidia and oospores is also explained. After 

 noticing that the direction, branching, and size of the parasites 

 depend upon the special peculiarities of certain corals, the author 

 discusses the classificatory position of the vegetable form. Naming 

 it Achhja penetrans, he suggests that it belongs to a group whose 

 life-cycle is complicated by marine and subaerial conditions, and 

 infers that Achlya, Sajjrolegnia, Botrytis, Peronospora, Empusina, 

 and possibly Bryopsis are so many names of the same organism 

 under these different conditions. Believing in the necessity of an 

 arbitrary name, he prefers that of Achlya. Finally an instance of 

 a parasite resembling what is called Saprolegnia ferax, Ktz., in a 

 littoral coral is given. 



May 18, 1876. — Dr. J. Dalton Hooker, C.B., President, in the Chair. 



" On the Organization of the Fossil Plants of the Coal-measures. 

 — Part VIII. Ferns (continued) and Gymnospermous Stems and 

 Seeds." By Prof. W. C. Williamson, F.R.S., Professor of Natural 

 History, Owens College, Manchester. 



Ferns (continued). — Under the name of Rachiopteris corrugata 

 a small stem of a fern is described, the outer surface of the bark of 

 which is corrugated with innumerable transverse ridges and fur- 

 rows. It has a vascular axis in its centre composed of several 

 clusters of barred vessels filled with tylose, which clusters are 

 blended together at their periphery, forming a cylinder ; its centre 

 is occupied by a cellular medulla, mingled with, small vessels, which 

 sends off radiating prolongations into the vascular cylinder, par- 

 tially separating the bundles of the latter. Beside this cylinder 

 is a second, smaller, isolated oval bundle, which soon escapes from 



