Palconfolugical Speculations. — Gratacap. 91 
animals belonging to the Mollusca which are found in the 
archibenthal and abyssal regions, especially the latter, do not 
live in a perpetual state of conflict with one another. A certain 
amount of contention and destruction doubtless goes on, but on 
the whole the struggle for existence is against the peculiar- 
ities of the environment and not between the individual mol- 
lusks of the area concerned. It is an industrial community, 
feeding, propagating and dying in the persons of its members 
and not a scene of carnage where the strong preys upon his 
molluscan brother who may chance to be weaker. Hence the 
course of evolution and modification, though still complex, is 
certainly much less so than in th shallower parts of the ocean." 
Now in the early seas there were probably no depths comparable? 
with the abyssal spaces of modern oceans. The fauna which 
arose and may have been partially contemporaneous with the 
Cambrian and which as a stratigraphic fact we find overlying 
the latter, was evolved in an offshore, and not necessarily pro- 
found basin. If freedom from competition and from destructive 
foes is true today in deep sea animals it was, especially as 
fishes were absent, more markedly true of these primal groups, 
and this may have produced that uniformity, a general evenness 
and similarity of shell-life, without strong or salient variations, 
which certainly is apparent in the Cambro-Silurian beds of 
fossils. 
At any rate it is certain that passing into the next section of 
the Hall fossils we encounter the evidences of a new fauna, one 
especially emphasized by the discoveries in Vermont of Profs, 
Brainerd and Seely. It is a limestone fauna, a deep sea 
fauna, and its development upon a scale of such magnitude 
with such diversity of fauna, with such a systematic zoological 
overthrust upon all Cambrian precedents, leads clearly to the 
conclusion that its growth extended far back in time and 
brought it, at its inception, into contemporaneity with the shore 
fauna of the .Cambrian formations. Size and skeletal mass 
are now very obvious in molluscan life. 
Conditions of life were probably identical with those of to- 
day so far as the propagation and maintenance of genera and 
species were concerned, and, as today extreme deep sea (abys- 
sal) areas are inimical to animal abundance, the faunas, suc- 
ceeding the Cam1)rian, if formed in deep water, may have 
