PROF, T. M‘K. HUGHES ON SPONGIA PARADOXICA. 279 
that it might possibly be the cast of a horny sponge. He was not 
prepared himself to offer a suggestion as to their nature. 
Prof. T. Rupert Jones thought that there were no grounds for 
not regarding them as some kind of organic structure, either sea- 
weed or sponges, or something else. The absence of structure was 
no argument against their organic origin; in many fossils the outer 
form remained, but all structure had disappeared. He did not 
attach much importance to the proportion of phosphoric acid in the 
matrix and supposed fossil. 
Dr. Woopwarp recalled a similar case as occurring in the London 
Clay at Harwich. He stated that similar pseudo-organic forms 
might be seen in course of formation in the sand at Bournemouth. 
He referred to the Harlania of the Niagara Limestone, and similar 
forms in the Nummulitic rocks of Egypt. The fact that such 
forms were found in strata of all ages pointed to their inorganic 
origin. 
‘Tore AvutHor said that from its great extent and manner of 
occurrence the whole mass could not be referred to any organism, 
though parts might resemble some sponges in form. ‘The position 
of the branching ,masses and their sections pointed to a concre- 
tionary origin. What most resembled organic structure in S. para- 
doxica, viz. the stag’s-horn pattern, was exactly simulated on many 
limestones and on gypsum, where the fretted surface was produced, 
not by weathering above ground, but in the red marl in which the 
gypsum occurred. 
