464 TRANSACTIONS OF SECTION C. 
DEVONIAN. 
So far as I am aware, there is only one recorded occurrence of Calcareous 
Algze from the Devonian rocks of Britain—namely, the Hope’s Nose limestone 
of Devonshire, from which Mr. Wethered *° has described aggregations of tubules 
resembling Gurvanella, but ina very poor state of preservation. It is hoped that 
this meagre record will be increased in the near future. 
Foreign Devonian. 
On the Continent the reported occurrences are, so far, equally poor. At the 
same time, the cursory examination which I was able to make of the thin sections 
of the Devonian limestones exhibited in the Brussels Museum leads me to expect 
that a careful investigation of the Belgian Devonian limestones will yield other 
examples besides Spongiostroma. 
CARBONIFEROUS.,. 
We now reach the period in Paleozoic times when Calcareous Algve attained 
their maximum development in England, a development rivalling that which 
obtained in the Ordovician rocks of Scotland and the Gotlandian of the Baltic 
area. The genera represented include Girvanella, Solenopora, and Mitcheldeania, 
while in addition to these there occur several lime-secreting organisms which, 
though still undescribed, will, I think, ultimately come to be included among 
the Calcareous Alge. The most interesting of these organisms I have recently 
figured from the Lower Carboniferous rocks of Westmorland, where it forms a 
definite zonal horizon or ‘band.’ *® For this form, on account of its strati- 
graphical importance and for facility of reference, I propose the generic name 
of Ortonella.”’ 
Again, at the same horizon in the North-West Province I have frequently 
noticed concretionary deposits of limestone which occur as finely laminated 
masses, the lamin often lying parallel to the general direction of the bedding 
planes, which, on microscopic examination, show no definite or regular structure, 
but have every appearance of being of organic origin. Many of these puzzling 
forms resemble very closely the somewhat obscure structures found in the Visean 
limestones of the Namur basin in Belgium, of which beautiful thin sections 
are displayed in the Natural History Museum at Brussels,*® and which Girich 
has described and figured under various names—Spongiostroma, Malacostroma, 
&c., and which he has included under a new family, the Spongiostromide,** and 
a new order, the Spongiostromacee. He gives the following definition of the 
family : ‘ Organismes marins, incrustants, coloniaux, a structure stratifiée. La 
structure de la colonie est indiquée, a l’état fossile, par la disposition de petits 
grains opaques (granulations), entre lesquels il y a des interstices, tantot plus 
étroits, tantot plus larges—canaux du tissu et canaux coloniaux—donnant 
Naissance & un tissu spongieux. Dans plusieurs formes, on a observé des 
Stercomes,’ and suggests that they may possibly have been encrusting 
foraminifera. 
I must confess that neither in the original sections nor in the beautiful 
iliustrations which accompany his work, can I see any grounds for referring 
these structures to the Protozoa. 
As regards the British specimens, I have long regarded them as due, directly 
or indirectly, to the work of Calcareous Alge, partly on account of their intimate 
association with well-developed examples of these organisms, and also on 
account of the entire absence of foraminifera and other detrital organisms 
wherever this structure occurs. As, however, I have little doubt that they 
are closely connected in their mode of origin with the Belgian specimens, we 
tnay conveniently speak of them under the general term Spongiostroma. 
Some of the best examples known to me occur associated with Ortonella in 
# Q.J.G.S., 1892, vol. XLVIII., p. 377, pl. ix., fig. 3. 
46 Q.J.G.S., 1912, vol. LXVIII., pl. LXVIL., fig. 2. 
47 From Orton, a village between Shap and Ravenstonedale, where this organism 
occurs in great abundance. 
48 One of these is also exhibited at the Jermyn Street Museum. 
49 Op. cit. (2). 
