118 TRANSATIONS OF THE [FrEs. 23 
The other deposits of phosphates known to me do not show 
very close analogies to ours, or are similar in their occurrence 
to those above mentioned. 
Ortain.—The origin of the Hanford Brook nodules cannot be 
considered as decided by this investigation ; but some con- 
sideration may be noted, bearing on what seem to be the most 
probable methods of formation. 
The only one that has as yet been suggested for them is that 
they may be coprolites. In this case they must be referred to 
some animal much larger than any known from this formation ; 
the animal might, however, as has been suggested by G. F. 
Matthew, have been soft-bodied, and hence not preserved, and 
there are indirect evidences of the existence in the Cambrian 
seas of some large soft-bodied animal probably related to the 
squids. But the trilobites found in the nodules are only 
occasionally comminuted ; generally they are complete heads ; 
occasionally complete bodies. In Zone 2 especially, but to some 
extent also in Zone 3, there is usually a nucleus which is 
sometimes a single trilobite test, sometimes two or three, or a 
number of fragments. The material collects rather on the 
inner side of the test than on the outer. Were the nodules 
coprolites, one would expect to find the tests thoroughly 
comminuted, and evenly distributed throughout the mass. 
Another view, applicable especially to those of Zone 2, would 
consider them as fossil sponges which, like those of the English 
Greensands, have had their organic matter replaced by 
phospate of lime or iron. The occurrence of spicules 
and gemmules, the regular shape and uniform size, and 
the frequent presence of a central part of different tinge from 
the rest, indicating perhaps a cup-shaped or hollow centre‘ 
favor this view. The darker rim of the nodule is similar to 
that observed in those of the English deposits. The compara- 
tive scarcity of spicules and absence of any trace of canals, 
might be explained by considering the sponge to have had 
keratose or calcareous spicules, and to have beeu much decom- 
posed and shrunken before phosphatization. Or there may 
never have been any canals, but only the central opening. The 
presence of the foraminifera and other foreign godies might 
be explained by supposing them to have drifted into the openings 
after the death of the sponge. But the trilobites are not so 
easily accounted for, as they often traverse the nodules from 
side to side in a way that would seem inconsistent with the view 
of the latter being fossilized sponges, And they are not cup- 
shaped, as far as can be seen by the eye, but regularly round 
