Calvin on the Hamilton in Ontario. 85 
and coarse plications on each side of the mesial fold and sinus; 
the hinge line is relatively short, in some rare instances it is not 
greater than the length, though on the average it varies from 
two to three times the length; the mesial fold and sinus are not 
<iivided, and the imbricating concentric striae are much more 
pronounced. Altogether the expression and characteristics of 
the shell are as different from those of the variety occurring in 
the lower beds as could well be imagined. 
With the short-winged spirifers are associated Cyrtia ham- 
iltonensis Hall, a small form of Athyris spiriferoides Eaton, 
Leiorhyfichus laura Billings or L. fmdticostus Hall, Chonetes 
scitula Hall, Strophodoizta 7iacrea Hall, and Callopora iticras- 
sata Nicholson. These are all more or less abundant and con- 
spicuous, though it must be admitted that in numbers and 
consequent prominence, 6". viucronata overshadows all the rest. 
The only crinoid found in the upper division was a Taxo- 
C7-inus^ probably T. (^Forbesiocrinus^ lobat-MS Hall. Two entire 
specimens of Dalmanites boothii Green, were found in the cut 
near Widder, and three other specimens were collected at the 
corresponding horizon a mile or so below Bartlett's Mills. 
PygiJia of Dalmanites are more or less common, and seem to 
have been the only parts of this trilobite seen at these localities, 
by Dr. Nicholson. 
Here then we have three distinct faunas, or at least, if we 
may not use the term fauna in such restricted sense, we have 
three distinct assemblages of sj^ecies in a section of about 250 
feet. There is nothing to indicate any break in the continuous 
and orderly process of sedimentation from the beginning to the 
end of the time represented by all three of the divisions. 
Neither do the sediments, so far as lithological characters are 
concerned, change materially so as to indicate any change in the 
direction of the currents that carried the material to the place 
it now occupies. Bluish argillaceous shales, with here and there 
thin layers more or less calcareous, characterize all three of the 
divisions. It is true that the upper part of the third division 
is yellowish, and contains more than the usual proportion of 
calcareous matter, but the change indicated seems not to have 
affected the fauna, since the species of the latest beds range 
down into beds that are lithologically identical with beds of the 
