the possibility of their being related to the calcareous Algae 

 must be considered. The testaceous Protozoa are not pro- 

 minently developed in the lower Palaeozoic rocks, and when 

 they do occur are, mostly, inconspicuous. On the other hand, 

 Cryptozoon reached, relatively, gigantic proportions. Dawson 

 says : "The larger masses are from one to two feet in diameter." 

 It seems probable that Cryptozoon is a primitive type that 

 does not closely accord with any of our existing phyla, but 

 may be an ancestral form of the Stromatoporoidea, or some 

 other group of the calcareous Hydrozoa. The silicification of 

 the fossils is undoubtedly pseudomorphic in its origin. They 

 were, no doubt, originally calcareous, and in the case of one 

 species, described in this paper, the silicification is present 

 only to a very limited degree. 



In dealing with so ancient an organism of doubtful affinities 

 it is difficult to determine what particular features are of 

 specific value. The Australian specimens exhibit a close re- 

 semblance to the generic type, but appear to be distinguish- 

 able from all hitherto described species in some particulars. 



Cryptozoon australicum, sp. nov. 

 Plates i. and ii. 



Skeleton consists of columnar growths which, in transverse 

 sections, are circular or sub-circular. Average diameter of 

 columns, § in. ; with a range of variation from ^ in. 

 to 2 in. in diameter. No peripheral wall. Each column 

 is built up of closely-set laminae, of varying thickness, which 

 are either concave or convex to the direction of growth. ( 8 > 

 The laminae are situated about one millimetre apart (about 

 25 laminae to the inch), and are sometimes crenulated or wavy. 

 The laminae, which in the fossil condition comprise the entire 

 skeleton, consist of earthy or siliceous material which is not 

 acted upon by acids, and under a magnifying lens exhibits a 

 very minute labyrinthic or spongiform structure. The spaces 

 between the laminae are filled with a fine, granular, calcareous 

 material identical with the rock mass in which the fossils are 

 embedded. As a rule the columns are separate and exhibit 

 a regular parallelism of growth. 



(8) The fragmentary condition of the specimens make this point 

 somewhat uncertain, as it is at times difficult to determine which 

 is the right way up of the columns. It is assumed, however, that 

 the thicker end of the column is the growing end, and, on this 

 evidence, where it is available, it would appear that the laminse 

 may take either an upward or downward curve, or be flat in the 

 centre and then turned either upwards or downwards when 

 approaching the periphery of the column. These variations may 

 prove to be only accidents of growth. 



