430 Corresjjondence — Mr. J. E. Marr. 



in the recently issued volume for 1886. I imagine there are very 

 few general geologists who desire to possess 15 plates of one species 

 of plant, however curious and interesting that plant may be. Again, 

 the appearance of seven plates devoted to the horns of Deer is not 

 likely to be welcomed by any but a few experts. These 22 plates 

 would have illustrated 50 or 100 species of Mollusca, and there are 

 nianj'^ hundreds of such fossils awaiting illustration. 



Why are the Mollusca so neglected? It is true that in this 

 volume we have the first parts of two memoirs on Jurassic Mollusca, 

 but one of these parts is wholly taken up with strati graphical details 

 which, though unquestionably useful, might perhaps have been 

 condensed or printed elsewhere ; this, however is a minor point, 

 a.nd every one will welcome Mr. Hudleston's Monograph. Cannot 

 the Council induce other palaeontologists to prepare similar mono- 

 graphs on the Ceflialopoda, Gasteropoda, and Pelecypoda of the 

 Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Cretaceous, 

 Eocene, and Oligocene formations ? 



I can testify that the synonomy of some of the commonest Chalk 

 fossils is in the utmost confusion ; and that Monographs of the 

 Cretaceous Mollusca would be welcomed by many amateur and 

 professional geologists. When will Mr. Wiltshire give us his 

 promised contribution ? I feel sure that if this and other Molluscan 

 Monographs were produced, and if those relating to fossil plants and 

 bones were deferred, the publications of the Society would be used 

 by a much larger nuinber of persons, and consequently that many 

 more geologists and local institutions would decide to become sub- 

 scribers. 



Hauwell, Berks, August 5. A. J. Jukes-Bkowne. 



THE GLACIAL DEPOSITS OF SUDBURY, SUFFOLK. 



Sib, — I owe an apology to Mr. Jukes-Browne for having omitted 

 any reference to the action of coast-ice in my paper upon the Glacial 

 Deposits of Sudbury in the June Number of the Magazine (pp. 262- 

 270). In considering the suggestions made to account for the con- 

 tortion of drift deposits, I should have mentioned the grounding of 

 true or false icebergs, or of coast-ice. Nevertheless, it seems to me 

 that the arguments I brought forward against the contortion having 

 been produced by icebergs apply equally to the case of coast-ice. 



Unless we are prepared to admit that the drifts were actually 

 frozen into the coast-ice at the time that the contortion was produced 

 in them (and I fail to see how such could be the case, considering 

 the uniformity of succession and characters of the drift over a con- 

 siderable area), we must suppose that they were deposited on the 

 sea-floor before the exertion of pressure by this ice. If so, it is 

 difficult to see why the drifts were not frozen as well as the under- 

 lying Tertiary rocks, for these drifts are of some thickness, and 

 considerable time must have elapsed during their formation. If they 

 were so frozen, the Tertiary beds ought to be affected in the same 

 manner as the drifts, which is not the case. 



