298 J. H. Collins — Cornish Serpentines. 



best for the present to class the Dyas, neither under Palaeozoic nor 

 Neozoic, but as a period of transition between these two great eras 

 in the development of life. 



I have kept the old divisions of the Trias, though I admit the 

 desirability of eventually abandoning them, and of adopting the 

 marine sequence of the Alps as a type. By that time, })erhaps, 

 a better name for the system may be found, and the Rhastic may 

 then be included in it. In Britain the Penarth Beds link them- 

 selves rather to the Lias than to the Trias, but this may be because 

 our Trias is not marine. 



In the Cretaceous system I have degraded Neocomian to its proper 

 subsidiary rank as a stage of the Lower division. The use of the 

 term for the whole of this lower series is an unwarrantable and 

 unnecessary innovation, which can only result in confusion. The 

 true Neocomian of Southern France seems to be the marine repre- 

 sentative of our Wealden, and no part of it corresponds to our 

 Lower Greensand. This last name and its correlative, Upper 

 Greensand, are certainly doomed to abolition ; the Lower Greensand 

 can be studied so well in the Isle of Wight, where the labours of 

 Edward Forbes added so largely to our knowledge of it, that no 

 name can be more appropriate than Vectian ; and I regard the 

 introduction of a new name as preferable to the adoption of the 

 French names Aptien and Urgonien. The Gault and Upper Green- 

 sand require further investigation, so I leave them for the present. 



My reasons for admitting only two systems in the Tertiary, and 

 for giving new names to these, have already been explained. 

 Quaternary, Post-Tertiary, and Post-Pliocene I I'egard as unnecessary 

 and unscientific terms. 



III. — On the Geological Histoky of the Cornish Serpentinous 



Rocks. 



By J. H. Collins, F.G.S. 



1. — The Lizard Serpentines. 



THE remarks by Professor Bonney on Dr. Sterry Hunt's recently 

 published " Geological History of Serpentines," which appeared 

 in the September Number of the Geological Magazine, open up 

 a very wide question — a question which broadly divides the non- 

 chemical from the chemical geologists and petrologists. Dr. Sterry 

 Hunt is well able to take care of himself in this discussion, and 

 certainly I have no present desire to take part in it except so far as 

 it relates to the Cornish areas, some of which are therein referred to. 

 These I have especially studied, and with respect to them I feel 

 bound to say that I find myself able entirely to agree with the 

 conclusions of Dr. Sterry Hunt. 



One of the regions in question, that of Porthalla, has also been 

 referred to by Mr. Alexander Somervail, in a letter which appeared in 

 the Geological Magazine, 1884, Dec. III. Vol. I. p. 479. This letter, 

 however, brings forward neither new facts nor new arguments 

 — it merely sets my conclusions (see my paper read before the 



