420 Dr. W. B. Carpenter o)i Otto Ilahus 



containing prisms of crystallized quartz, must be regarded as a 

 mere rock-formation, a product of purely Mineral agencies. 

 But Geologists wlio have carefully studied it are satisfied of 

 its stratigraphical continuity with a limestone of whose organic 

 origin there can be no reasonable doubt ; and they find an 

 adequate reason for its metamorphism in the intrusion of the 

 igneous rocks which it adjoins. 



4. Again, Dr. Hahn leaves altogether out of view the yewera^ 

 evidence of the organic uatm'C of Eozoon afforded by the dis- 

 position of the beds of Eozoic Limestone, which strongly 

 impressed Sir William Logan (than whom no judge could 

 have been more competent) with its similarity to a Coral-reef. 

 And, in like manner, he takes no account of the conformity 

 in the condition of its calcareous lamellte to that of the earliest 

 undoubted fossils [Stromatoporaj Recejitaculites, &c.) of the 

 Silurian limestones, which has been specially urged by Dr. 

 Dawson. Neither does he give any evidence of having him- 

 self instituted such comparisons, which have obviously a very 

 imjDortant bearing on the question 5 nor does he show that he 

 has given any attention to the manner in which indubitably 

 Organic sti'ucture and Mineral arrangement may be blended 

 in the same fossil, — a point (notably seen in Echinoderm 

 fossils) to which I have myself repeatedly drawn attention in 

 the coui'se of this controversy. To him, as to others who 

 take the same side, evidence of Mineralization seems sufficient 

 to settle the whole question ; and nothing ought to be accepted 

 as a Fossil, which does not exhibit all the structural characters 

 of the organism it is affirmed to represent. I could scarcely have 

 supposed that any person trained in habits of scientific reason- 

 ing could have expressed himself as follows : — " It is only if 

 all the essential characters of the Foraminifer, and indeed each 

 for itself, are no mere rock-structures, that the proof from 

 analogy is carried at least to a high degree of probabilit}\ 

 But if the inorganic nature of only one is proved, the chain of 

 evidence is broken''^ (p. 275). Li other words, no fossil can 

 be accepted as such, however close may be its morphological 

 correspondence with some recent type, if its originally organic 

 structure has given place to crystalline aggregation ; and the 

 multitudes of shells preserved in Oolitic beds, whose external 

 forms are most perfectly preserved, but whose shell-substance 

 is represented by large crystals of calcite resembling brown 

 sugar-candy, must be regarded, according to Dr. Hahn, as 

 mere pseudomorjyhsl 



5. The following extract will afford to the Palaeontologist 

 Bome means of judgment as to Dr. Hahu's qiialifications to 

 discuss a question which is at least as much Fala'outological 



