84 
THE MIDDLE LIAS OF NORTHAMPTONSHIRE. 
involuntary desire, acting on the mind without intervention 
of reason, motive, or deliberation, but tending uniformly and 
exclusively to the preservation of the individual or propagation 
of the race.” 
What I want to be shown are some of the so-called 
transition stages, or else positive proof that a given species 
formerly constructed its nests quite differently. 
The subject I have addressed you upon is, I know, a 
very debatable one, and it is quite possible, with the mass of 
evidence, both for and against, to make a strong case for 
either side ; but before I alter my views, I want more con¬ 
clusive evidence, when I shall be quite willing to do so. 
I sincerely hope that others, with more time and ability than 
myself, will take this matter up, and endeavour to elucidate 
some of its mysteries. This must be my excuse for troubling 
you with what I fear has been a very uninteresting address 
and allow me to express my grateful thanks for the very 
courteous attention with which you have listened to me. 
THE MIDDLE LIAS OF NORTHAMPTONSHIRE. 
BY BEEBY THOMPSON, F.G.S., F.C.S. 
PAKT IV. 
The Middle Lias Considered as a Source of Water 
Supply. 
(Continued from page 298 , Vol. IX.) 
There is, perhaps, no social question of greater importance 
at the present time than that of the supply of pure water to 
large towns; and since many people seem to have the idea 
that Water Companies or Corporations can always get 
abundance of water if they will only go to the trouble and 
expense of digging, or boring, or some such operation, 
I have thought it advisable, as a prelude to the scheme I 
have to propose for the water supply of Northampton and 
district, to consider the various possible sources of water and 
the reasons of their failure, or for or against their rejection 
as a supply to that district; an additional reason being that 
I shall endeavour to show later on how some of these 
inadequate sources may be made helpful to the Marlstone 
supply. 
