J. Malcolm Madaren — The Waters of Geysers. 511 



the zone of H. snhglohosufi of Wiltshire and Berkshire, but has not 

 yet been reported from Hampshire, Kent, Isle of Wight, Dorset, 

 Oxfordshire, Buckinghamshire, or Hertfordshire. 



With regard to Acanthoceras rotomagensis it cannot be regarded as 

 a better guide than IT. snbglobosus, for in many of the southern 

 counties it is fairly common in the zone of A. varinns. North of the 

 Thames, however, it seems to be restricted to the higher zone until 

 we reach Norfolk, where it again occurs in the zone of A. varinns, as 

 it does also in Yorkshire. 



There remains only the larger form of Discoidea cylindrica, a species 

 which is generally much more common in the upper part of the 

 Lower Chalk than in the lower part. In the south of England it 

 has only been recorded from the zone of A. varians in Dorset and 

 Somerset, and by Mantell from Hamsey in Sussex (not since 

 confirmed). It is indeed a common fossil of the lower zone in 

 Yorkshire, Lincolnshire, and Norfolk, but the form there found is 

 the depressed variety, and if any constant structural differences can 

 be found to distinguish this variety from that which prevails in the 

 higher zone the latter might perhaps be utilised as an index for 

 that zone. 



To sum up, therefore, it would seem that our knowledge of the 

 distribution of the fossils of the Lower Chalk is not yet sufficiently 

 complete to enable us to decide on any substitute for H. suhglobosus 

 as an index. It may be that Kaploceras Austeni would be a better 

 one in spite of its occasional occurrence lower down, or it may be 

 that the taller hemispheric variety of Discoidea cylindrica will be 

 preferable. More information is required about both, and meantime 

 I am sure that it would be undesirable to make any alteration in the 

 current nomenclature, and I do not think that the terminology 

 proposed by Mr. Bosworth would at any time be an improvement. 



V. — The Soukce of the Waters of Geysers. 



By J. Malcolm Maclaren, B.Sc, F.G.S., 



Geological Survey of India, Calcutta. 



PROFESSOR SUESS has somewhat recently stated his belief that 

 the waters of all geysers and boiling ' pulsating ' springs and 

 of some mineral springs are of ' hypogene ' or direct magmatic 

 origin (Abstract Geog. Journ., vol. xx, p. 518). 1 am unfortunately 

 unable in this backwater of science to verify the abstract by 

 reference to the original (Gesell. Deutsch. Naturforscher und 

 Aertze, 1902). With his belief, however, several prominent 

 Continental and American geologists have expressed their con- 

 currence, and some have indeed amplified the hypothesis to cover the 

 origin of metalliferous deposits near igneous contacts. For example, 

 W. H. Weed (Trans. Amer. Inst. M.E., vol. xxxiii, p. 746) says : — 



" I hold that the metallic contents of such veins are not gathered 

 by ordinary meteoric water, as maintained by Van Hise. The water 

 content of the sedimentary rocks (ground-water) present at the time 

 of eruption was expelled by contact- metamorphism. The ore- 

 forming solutions were in part of direct igneous origin (i.e. primitive 



