Dr. A. Smith Woodward — A Triassic Reptile from Brazil. 251 



in the " Bournemouth " Well, but in all other wells, and the exhaustion 

 is certainly felt as far as Kingston Lacy, two miles distant. The total 

 yield of water is anticipated at 3 million gallons per day. 



Attention should be drawn to the difference between the Bovington 

 and Wimborne waters as regards their mineral contents ; and, con- 

 sidering that they both proceed from the Chalk, this is all the more 

 remarkable. The amount of solids obtained by evaporation in the 

 case of the Bovington water, according to an analysis made at 

 Devonport, is returned at 16 '8 grains per gallon. Of this amount 

 carbonate of lime contributes but little, whilst the chlorides are 

 comparativeljr abundant. Hence the water must be soft. The 

 analysis of the water of the Wimborne waterworks shows 22-19 

 grains per gallon, of which 14- 8 grains may be expressed as carbonate 

 of dime. Thus the Wimborne water is fairly hard, and much pains 

 are taken to soften by artificial means the supply intended for 

 Bournemouth. 



It is evident that position with regard to existing contours is an 

 important factor iu an artesian well, and the valley of the Allen at 

 Wimborne seems to fulfil the requirements of the case in a remarkable 

 degree. But there is also another element in the problem, viz., the 

 character of the Chalk encountered during operations. It has been 

 said that permeability in the Chalk depends not so much on the nature 

 of the Chalk itself as on the fissures by which it is traversed. This is 

 well illustrated by the experience of the headings in the Bournemouth 

 Waterworks at Wimborne. At the same time it is not incorrect, in 

 a general sense, to regard the Chalk formation, with very limited 

 exceptions, as a sponge, owing to the facility with which the water- 

 level moves up and down, according to the amount of rainfall in those 

 areas, such as the Hampshire and Wiltshire plateau, where the Chalk 

 itself forms the surface. That the surface contours, and consequently 

 the surface-flow, has some influence on the underground flow may be 

 conceded, yet the controlling factors of the latter are in the main 

 " the difference of pressure along the lines of flow, the varying texture 

 of the strata traversed, and the disposition of contiguous impermeable 

 strata." ^ In regard also to the degree of artesian pressure existing at 

 any given spot, this may sometimes be modified by the action of 

 springs, which, like excessive pumping, tend to bleed the underground 

 arteries, and thus lower the general water-level for considerable 

 distances. 



III. — On some Fossil Heptilian Bones from the State of Eio 



Grande do Sdl, Brazil.^ 



By Arthur Smith Woodward, LL.D., F.R.S. 



A FEW fossil reptilian bones discovered by Dr. Jango Fischer m 

 1902 at Santa Maria da Bocca do Monte (Serrito) in the Rio 

 Grande do Sul, which have been submitted to me by Dr. H. von 



^ Baldwin-Wiseman, on tlie "Motion of Sub-surface Water": Quart. Journ. 

 Geol. See, vol. Ixiii, p. 98. A sketch-map of sub-surface water-levels in the Chalk 

 of Dorset, Wiltshire, and Hampshire is appended to this paper. 



- Reprinted from Eevista do Museu Paulista, vol. vii (1907), pp. 46-57. See 

 also abstract in Kep. Brit. Assoc, 1903 (1904), p. 663. 



