64 THE HAMILTON ASSOCIATION. 
confined to the upper or glaciated portion of the chert. Such, 
however, is not the case: and the two species already described 
by no means represent the complete ‘‘ genera’’ of this remark- 
able Hydrozoa. Some appear to have been ‘‘ free floaters ”’ 
in the ancient Silurian Sea while others were moored to the sea 
bottom by a single stem. Asin the case of a Dendrograptus 
which came under observation of the late Palaeontologist of 
the Dominion Geological Survey, Prof. E. Billings, I am 
inclined to believe in some instances the fossil perhaps in rough 
weather severed its ties with the part buried in muddy 
sediment, and went away cruising independently, trailing 
the stem behind. Still the appearances which led to 
the conclusion may be deceptive in the case recorded by 
the Canadian Palzontolagist, as well as in others which 
came under the writer’s personal observation. That free 
floating Sertularians existed, in the American Mediter- 
ranean Seas, both in Cambro-Silurian times and also when 
our local rocks were deposited subsequently, can hardly be 
denied (the evidence is too strong for refutation) but it is no 
less clear that the great majority of these organic remains 
discovered here had either spreading, funnel-shaped or bul- 
bous roots unplanted in the sea bottom. One of the grapto- 
lites most frequently found in this locality is Dr. James Hall’s 
Dictyonema. It may be necessary here to give the exact words 
used by the Great United States paleeonotolgist in describing 
the Genera, because I was rather puzzled to find a form figured 
as such erroneously in the old country perhaps, viz.: General 
characters—fronds, consisting of flabelliform or funnel-shaped 
expansions (circlar from compression composed of slender, 
radiating branches which frequently bifurcate as they recede 
from the base). Branches and subdivisions united laterally by 
fine vinetransverse disepiments. Exterior of branches strongly 
striated and often deeply indented. Inner surface Celluliferous | 
or serrate as in graptolithus.’’ In the Hydrozoon Dictyograptus 
(Dictyonema) sortale of Europe as figured, I am unable to 
discover any lateral bars whatever. Even Dr. Hall’s descrip- 
tion of the family must be modified owing to more recent 
