Correspo7idence. 477 



of some old river-terraces, of wMch, however, tliere are no examples as 

 far as I have observed. On the other hand — from the elevation 

 attained by the Drift, and erratic blocks on these hills— it is be- 

 yond question that at the Post-pliocene period nearly the whole 

 country was submerged : and it is less incredible (to say the least of 

 it) to assume the agency of the sea in the formation of these valleys 

 (or parts of them), which we know was there, than that of a stream 

 of which there is no trace. 



The more I consider this subject the more I am satisfied that, in 

 the great majority of instances in this region, the extent and limits 

 of river action are capable of the clearest demonstration. Most of the 

 valleys are really double valleys, or valleys within valleys, the 

 smaller being alone due to river denudation. This is a subject, 

 however, on which I have more fully stated my views in the pages 

 of a contemporary,^ and shall not further "allude to at present ; but 

 before the enthusiastic advocates of sub-aerial denudation for all 

 valleys can exjDect their views to meet with general acceptance, they 

 must explain the origin of valleys without rivers such as those of 

 the uplands of Yorkshire and Lancashire. 



I remain, your obedient servant, 



Edward Hull. 

 Geological Stjrtey of Great Britain, 

 Manchester, llth Sept., 1866. 



To the Editor of the Geological Magazine. 



Sir, — Permit me through the medium of your Magazine to direct 

 attention to some remarks made by Mr. J. W. Salter in the Appendix 

 to the Memoirs of the Geological Survey of Great Britain, Volume 

 m., lately published. 



In reviewing the group of Cystideans (page 284), which had been 

 so ably and philosophically handled in the preceding volume of the 

 Memoirs, by the late Professor Edward Forbes, then Palseontologist 

 to the Survey, Mr. Salter takes upon himself the responsibility of 

 expunging the identification Professor Forbes believed he had cor- 

 rectly made, of specimens collected by the Survey from Ehiwlas, and 

 Sholes Hook, in Wales, with Echinosphcerites (Sphceronites) aurantium, 

 describing them as a new species under the name of Sphceronites 

 stelluliferus ; the figures to illustrate this and the other fossils on 

 Plate 20 being transferred from the very fine engraving by Mr. Lowry, 

 originally made for Professor Forbes' article in vol. ii. part 2. 



As to the correctness of Mr. Salter's views with regard to the 

 structure of this singular group of Silurian Echinoderms, wherein he 

 differs from Professor Forbes, I do not at present intend to enter ; 

 I cannot, however, allow the remarks on some of these species to 

 remain imrefuted as I consider them unjust to the memory of one 

 so universally admired for the strict probity and con-ect scientific 

 observation, so characteristic of our late highly esteemed friend. 



The following are the passages I especially allude to (the italics 

 ^ The forthcomiHg number of the Popular Science Eeview. 



