68 
■■Notes on fossil Lithothamnia (so-called Nulliporae)/’ by 
Arthur Wm. Waters, F.G.S. 
The organisms on the table before ns have been assigned 
very various places in the organic or inoi’ganic kingdoms at 
different times. The recent ones have perhaps most often 
been placed among the corals, while the fossil forms have 
passed more frequently as concretionary. 
After shortly reviewing the opinions of some of the 
leading naturalists of this century, Mr. Waters drew atten- 
tion to a paper of Eosanoff, published in 1866,^ on the 
Melobesiacea, which he divides into three sections, the 
Melobesia, Lithophyllum, and Lithothamnium. In this 
paper full description is given as to their mode of growth 
and their reproduction. Since then Giimbel-f has published 
in 1871 an excellent monograph on the fossil forms under 
the title, ‘'Die sogenannten Nulliporen,” in which he estab- 
lishes 15 species. This paper has been largely used in pre- 
paring the present notes. 
As most present will know, they attain their greatest 
development in the the Leithakalk, a meiocene formation 
which is principalljq in some cases almost entirely, composed 
of this algse. Unger says he has never seen any which 
contains less than two thirds. Thus formations of vast ex- 
tent and many hundred feet thick, perhaps in some places 
thousands, are so largely composed of this limestone sea- 
weed. But it is in no way confined to the Leithakalk, being 
also very abundant in the eocene, especially the upper 
division ; the so-called granit-marmor, or Bavarian marble, 
a numulitic formation, is very largely composed of this con- 
cretionary-looking body. In North Italy it abounds in the 
eocene formations which are so largely developed in the 
Veronese and Vicentin. In many places the formation is 
some hundred feet, much more than half composed of the 
* Mem. de la Soc. Imp. des Sc. nat. de Cherbourg, t. xii. 
t Abhaud. d, E. Bay At. der Wissen, x., part i., 1871. 
