1862.] BIGSBY — CAMBEIAN AND HURONIAN. 41 



curious experiments, which consisted of sowing barley in powdered 

 rocks ; he found that whatever might be the age of the rock, provided 

 only that it belonged to a series in which organic remains were 

 present, the amount of phosphoric acid present in the crop exceeded 

 considerably that existing in the barley from which it was derived. 

 In Cambrian rocks Dr. Daubeny found no trace of phosphorus. 



We know that calcareous matter in Cambrian beds seldom occurs, 

 and only in small infiltrations, as in Wales, or in a thin and solitary 

 seam, as in Brittany. Where one or more large calcareous beds, 

 unfossiliferous, are observed in a group which seems to belong to this 

 epoch, the strong probability is that it belongs to the Huronian 

 series. 



e. Paucity of Fossils. — We also know that § 8, marking the im- 

 poverished life of the Cambrian, contains an important fact which 

 we are authorized to state, after a most pertinacious and skilful ex- 

 amination of its beds, in Wales and Ireland especially. Nor need 

 we expect any traces of life in the contemporary conglomerates of 

 Scotland and America. 



The frequent occurrence of conglomerates, grits, and sandstones in 

 this series forbids our attributing the absence of life in it to any 

 permanent abyssal depths, as was supposed by the late justly lamented 

 Daniel Sharpe*. 



The remains of organized beings in the Cambrian are few, both 

 generically or specifically, and they are mostly related to certain low 

 forms in the primordial zone of various countries ; for instance, the 

 Arenicola didyma, which corresponds to the Scoli thus (Annelid-tubes); 

 Palce&pyge Bamsayi, corresponding to the Trilobite (a high form, 

 however) ; the Oldhamia is a sea-weed (Goeppert) ; the plant Chon- 

 drites occurs also in the Silurian as a genus f. 



I repeat, then, that in this period we are not introduced to any 

 set of living creatures wholly unknown in later periods, as we are in 

 some other parts of the great sedimentary succession. 



Some of the reasons for the absence of organic remains from this 

 group of beds may be stated as follows : — 



1. The general absence of carbonate of lime, and the probable ab- 

 sence of phosphorus and other elements of organization. 



2. The great, continued, and occasionally tumultuary deposition of 

 sediment, in which few or no animals could have lived (James Hall). 



3. The deposition of substances unfit to support life, whether di- 

 rectly poisonous or because consisting of any unmixed material, as 

 clay, lime, silex, &c. 



4. Plutonic action, which was frequent in the Cambrian, operated 

 by modifying or destroying rocks and their contents; metamorphism, 

 which need not have been caused by subterranean heat, has the same 

 effect. 



5. Shells in porous or permeable strata are often removed by the 

 infiltration of solvent fluids J. 



* Quart, Journ. Geol. Soc. vol. id. p. 208. f Ibid. vol. xii. p. 246. 



\ See Mr. Prestwick's remarks, ibid. vol. viii. p. 245. 



