THE GEOLOGIST. 



must not expect many converts to his geological heresy unless he give us irresistibly con- 

 vincing proofs. We are not willing to close our columns against any expression of opinion, 

 however rash or wroQg it may at first sight appear, — the wildest might turn out right at 

 last ; but we cannot permit any further discussion of these Portland fissures, unless posi- 

 tive sections to scale with the position of these mammal bones or some practical details 

 are submitted to us. — Ed. Geol.] 



Age of the Trinidad Strata. 



Dear Sir, — Perhaps you will allow me to make a remark in connection 

 with a statement occurring in Mr. Guppy's paper on the Parian Forma- 

 tion of Trinidad. He mentions sandstones containing a Trigonia, Belem- 

 mites, and other fossils beloDging to a period represented by a series of 

 rocks on the continent of Europe, known as the ISTeocomian. What I wish 

 to suggest is, that it is more than probable that the beds in Trinidad were 

 not of Neocomian age, as Mr. Guppy says. Are we to suppose it pro- 

 bable, or even possible, that there was no variation of fauna in geological 

 periods, and that the occurrence of two or three species of mollusca to- 

 gether in different localities, furnishes proof of their existence ? Can 

 geologists point to certain species of shells, and say, ''Wherever these 

 are found together imbedded, we know the rocks containing them to have 

 been contemporaneous" ? 



Suppose the existing fauna of the world to become fossils, where should 

 we find species to characterize it? By what two or three species would a 

 geologist be able to distinguish the deposit from any that preceded it ? 

 Would he not be very likely to place the Australian beds as contempo- 

 raneous with our Oolites (the absence of Cephalopoda being the only re- 

 markable difference) ? and he would most probably, according to the system 

 now pursued in geological classification, assign a different period to nearly 

 every existing fauna. Geologists are, it seems, too much impressed with 

 an idea of " contemporaneity." As Professor Huxley said, in his Address 

 to the Geological Society, 1862, " it would have been very much better 

 for geology if so loose and ambiguous a word as ' contemporaneous ' had 

 been excluded from her terminology, and if in its stead some term express- 

 ing similarity of serial relation, and excluding the notion of time altoge- 

 ther, had been employed to denote correspondence in position in two or 

 more series of strata." Professor Huxley proposes to substitute the word 

 " homotaxis " as more correct, and avoiding the production of an erroneous 

 impression. Edward Forbes was in the habit of asserting that the simi- 

 larity of the organic contents of distant formations was prima facie evi- 

 dence, not of their similarity, but of their difference of age. It would be 

 well if geologists were more attentive to these facts. Many conclusions 

 which are now held as undeniable would be shaken from their foundations, 

 and geology would have a difficulty removed from her path which must 

 sooner or later make itself known. E. E. Lankester. 



Remarkable Coat-Plant. 



Sir,— I have lately found in a seam of coal a stem of Sigillaria which 

 throws considerable light on the compound character of some of our com- 

 mon Coal-plants, and tends somewhat to simplify a portion of fossil botany. 

 The circumference of the specimen is 1 foot 6 inches, and after the removal 



