( 544 ) 
[September, 
ANALYSES OF BOOKS. 
; 'terminal Forms of Life. By Professor John Cleland, M.D., 
LL.D., F.R.S. 
The substance of the pamphlet before us has been delivered as 
a LeCture in St. Andrew’s Hall, Glasgow, and has been re- 
produced in the “Journal of Anatomy and Physiology.” Though 
extending but to 17 pages it is, we do not hesitate to say, one of 
the most serious critiques on that phase of Evolutionism known 
as Darwinism — that is, the theory of the development of animal 
forms by “ accumulated chance variations ” — which have ever 
appeared. Prof. Cleland argues that on this supposition “ all the 
lines of development of forms will necessarily be indefinite ; that 
in them all, change, progressive as well as other, will be^occurring 
at the present time, very slowly, but as much as ever it did, and 
that it must continue to occur.” In opposition to this view he 
seeks to show “ that the animal kingdom is full of forms which 
when once reached (whether through uninteirupted lines of 
descent from a common ancestry or not) have no power to ad- 
vance further.” Such are what the author names terminal forms. 
As instances of such forms he mentions, firstly, the lamp-shells. 
One genus of these, the Lingula, is traced in one of the oldest 
fossiliferous rocks, and still exists at the present time without 
essential change. More complex lamp-shells, such as the Spirifer 
and the Productus, may also be traced back to the Old Red 
Sandstone. “ Since that time,” continues Dr. Cleland, “so in- 
effective have their accidental variations been in the struggle for 
existence that by far the greater number have become extindl, 
while they have left no other kind of animal behind them that 
by any possibility could be supposed to have had them among 
its ancestors.” 
As another case we find mention of the ordinary bivalves, such 
as the cockle, oyster, mussel, and scallop. They have indeed 
attained their maximum development at the present day, but 
“they have flourished from far-off Silurian times, and palaeontolo- 
gists describe from the Silurian rocks numerous species resem- 
bling pearl-oysters, cockles, and mussels. There is no reason 
to imagine that any of them have become ancestors during all 
the time since then of animals other than bivalves.” 
As a more striking example may be taken the cuttle-fishes : — 
“ Notwithstanding the high complexity of these animals com- 
pared with other invertebrates, their ancestors have not been 
