Calvin on the Hamilton in Ontario. 83-. 
ciated Cho7ietes lincata Hall, Tentactdites atte?nmtus Hall, ai 
small, very pretty spine-bearing Platyceras refen-ed, with some 
doubt, by Nicholson (Pal. Ontario, 1874,) to P. duTnosum 
Conrad, the interesting crinoid with movable spines — Hystri- 
crinus carpenteri Hinde (Ann. and Mag. of Nat. History, 
March, 1885), and Phacops rana Green. 
It is possible that Phacops is an exception to the rule I have 
stated regarding the limitation of species, and that it ranges 
through all three of the divisions into which the Hamilton sec- 
tion is palteontologically divided. Some of the specimens found 
associated with the species named above may have come from 
overlying beds of the second division. Nicholson reports it 
from near Widder where the exposure is wholly confined to the 
upper division, though my own observations are negative as to 
its occurence at that horizon. 
It may be said, by the way, that the generic name Hystri- 
crinus was proposed by Hinde (Mag. and date above cited) as 
a substitute for Anthroacantha of Williams (Proc. Am. Phil.. 
Soc. April, 1883), on account of the fact that Williams' name 
was practically preoccupied, the name Arthraca7ithus having 
been employed by Schmarda for a genus of Rotatoria in 1854. 
(See papers cited and also the paper of Hinde in Ann. and. 
Mag. of Nat. Hist, for March, 1886). Furthermore Wachsmuth 
and Springer (Revision of the Palaeocrinoidea, Pt. Ill, p. 117), 
are inclined to regard Hystricrinus carpe7iteri Hinde as proba- 
bly identical with Arthroaca?itha ftmctobrachiata Williams. 
The small Platyceras referred to is probably a new species,, 
or at least an unnamed variety. 
The middle division of the Hamilton section along the Aux 
Sables is characterized by the great abundance of corals. None 
of the species already named, excepting Phacops rana^ pass up 
into it. The list of species would be a very long one, but we 
may take Hcliophyllujn halli Ed. and H. as the typical form.. 
With H. halli we find associated Cystiphyllum americanum Ed., 
and H., and Heliophyllum juvene Rominger. Diphyphyllum 
archiaci Billings is a rare species found in the same association. 
The favositoid corals are represented by Favosites billingsi 
Rom., Favosites placenta Rom., Favosites arbuscula Hall, 
Alveolites goldj us si Billings Alveolites frondosa Nicholson, to- 
