﻿Cryptozoon and other Ancient Fossils. 209 



exhibit canals only in places. Elsewhere they may have 

 perhaps been destroyed by decay and pressure. Matthew 

 regards these forms as fossils ; and if so, they are 

 undoubtedly allied to Cryptozoon, if not properly belong- 

 ing to the genus. They are in any case the oldest known 

 forms referable to this type. In other beds of the same 

 age fragments of Eozoon showing the canal systems have 

 been found, and also needles supposed to be spicules of 

 sponges, and carbonaceous films and fibres which may be 

 of vegetable origin. 



III. General Eemarks on Cryptozoon and Arch.eozoon. 



If we endeavour in imagination to restore these curious 

 organisms, the task is a very difficult one. They no doubt 

 grew on the sea bottom, and must have had great powers 

 of assimilation and increase in bulk. Still, it must be 

 borne in mind that they were largely made up of inorganic 

 particles collected from the mud and fine sand in process 

 of deposition. The amount of actual organic matter in the 

 hard parts even of large specimens is not very great, and 

 the soft living material, if they were animal, must have 

 been confined to the canals and to tlie exterior surfaces. 



As the only marine animals known to accumulate 

 foreign matter in this manner are the Protozoa of the 

 Ehizopod type, one naturally turns to them for analogies, 

 and perhaps species of the genus Loftusia most nearly 

 resemble them in general arrangement. But this type is, 

 I believe, not known lower than the Lower Carboniferous ; 

 Z. Columhiana, A. M. Dawson, found with the genus 

 Fusulina in rocks of that age in British Columbia, being 

 the oldest known species.^ I am not aware that any of 

 the Stromatoporse, properly so called, as nearly resemble 

 Cryptozoon, unless my genus Megastroma from the Car- 

 boniferous of Nova Scotia is referable to that group. 



- Journal London Geol. Survey, Vol. 35, p. 69, et seqr. 



