Rev. A. Irving — On the Permian and Trias. 321 



certain strata which are better regarded as members of the systems 

 above or below it. 



3. Since there is (when certain unnatural appendages are lopped 

 off) a parallelism between the English Permian and the German 

 Dyas, while such a parallelism between the Russian series and either 

 the German or the English cannot be established, it seems that the 

 adoption of the name ' Permian ' for the group of strata known by 

 that name in English geolog}'^ bas been unfortunate : a better terra 

 by which to designate it would have been ' Post-Carboniferous ' 

 (D. ' Postcarbonisch '),a term applied to the group by good writers 

 both in England and in Germany. Personal esteem for the illus- 

 trious author of the former term will no doubt for a long time 

 continue to give a sentimental j^reference for its use in many 

 quarters. We should recollect, however, that this difficulty does not 

 exist among the younger generation of geologists, for the use of 

 whom mainly our text-books are written. In a science like geology, 

 nomenclature, and in particular classificatory nomenclature, should, 

 in the connotation of the terms used, be safeguarded against impli- 

 cation even of what may afterwards have to be unlearnt. 



4. Mutatis mutandis the remark last made applies to the term 

 ' Trias.' A Triassic order (in the sense in which the term is under- 

 stood in Germany) does not exist in this country. Mr. Ussher,^ 

 indeed, tells us of an unbroken succession of strata in the south- 

 west ; but even if the sequence of which he tells us there be never dis- 

 proved, it is clear that all that this gentleman has done is to establish 

 the continuity of a series of sandstones and mai'ls of Triassic age in 

 that part of England ; he has not any lithological grounds of a very 

 definite character, and no warrant from fossil-remains, for calling his 

 series a ' Trias,' much less for calling upon us to recognize this as the 

 normal facies of the English series. This much is certain, that the 

 series described in Mr. Ussher's paper do not answer to a correct 

 definition of the German Trias as a system which " divides itself 

 sharply into two sandstone- and marl-formations, the two being 

 separated by a limestone-formation with a marine fauna, which is 

 distinguished alike b}?^ poverty of forms and richness in individuals " 

 (Credner). On the other hand, we have, not a complete Triassic 

 system, but two definite formations (the Bunter and Keuper) of that 

 system in the midland and northern counties, which are undoubtedly 

 rocks of ' Triassic age.' The adjectival term ' Triassic ' is therefore 

 exceedingly useful in English geological nomenclature, though it 

 would seem advisable to discontinue altogether the use of the sub- 

 stantive word ' Trias,' as applied to our English strata. At the 

 same time, the term ' New Eed Sandstone ' is hardly suitable, on 

 account of its misleading connotation (and we cannot entirely dis- 

 connect the connotation from the denotation of such terms) ; ' New 

 Eed Series ' or •' New Eed System' would appear therefore preferable. 



5. As to the uppermost limit of the New Eed System, I should 

 agree with Mr. Wilson,- in putting the greenish marls in the Keuper 



1 Vi^e Q.J.G.S., vol. xxxiv. 



2 Vide Report of British Association, Section C, 1881. 



DECADE II. — YOL. IX. — NO. VII. 21 



