.m^ - - 1, 



"^fes.. 



Fig. 7<? Portion of ihin section of Cryptozoon proliferum {yi\d.g\\\'a^<\ x 50). 



(a) Corneous layers, (a^) One of these dividing, {b) Intermediate stroma with 

 granules of calcite, dolomite and quartz, traversed by canals. 



From a Micro-photograph by PROF. Penhallow. 



{To face p. 39. 



