10 
MUSEUM BULLETIN No. 31. 
.direction, and also in having a wider border of small plates. The 
arrangement is the same as in C. youn<$, but the lateral covering- 
plates are not so narrowly pointed on their inner ends. No median 
covering pieces have been seen. 
The specimen selected as the holotype is 18 mm. in diameter. 
This is one of the forms which have been identified usually as 
A. billingsi, but it persistently differs from it, as- well as from C. 
youngi in the points mentioned, and is intermediate in characteristics 
between C. billingsi and G. pileus of the upper Ordovician. 
Ray I of this species is almost straight, the only curvature being 
just at the point where it joins the peristomal plates. At the outer 
end there is no curvature. 
Ray IY is the most curved of any on the type and all show 
the greatest curvature at about half-way betwen centre and margin. 
Horizon and Locality. The holotype (No. 3235 Victoria 
Museum), was collected by W. A. Johnston from the Cystid beds in 
the Prasopora zone of the Trenton in an abandoned quarry near the 
entrance to Jackson park, Peterborough, Ont. The same form has 
been found in the Prasopora zone at Fenelon Falls and Brechin, Out., 
and in the Gystid beds at Ottawa, Out., and Hull, Que. 
Carney ella platys (Raymond). 
Plate III, figure 1. 
Ottawa Naturalist 1915, 24, p. 59, PI. 1, fig. 5. 
This species is based upon a single specimen which has long been 
in the Museum of the Geological Survey. It is imperfect, having 
been cut off by a joint along the anal side, thus losing the distal enus 
of rays I and Y. The specimen is otherwise quite well preserved. 
The outline is rounded-pentagonal , its greatest diameter being 24 
mm., and the arms are long, reaching nearly to the margin. The 
rays are nearly straight, though the posterior ones probably curved 
toward each other somewhat, partly enclosing the anal structure. 
Such a curvature is suggested by such parts as remain. The anal 
pyramid is entirely missing, but was probably small and far from 
the mouth. The inter-radial spaces are covered with small, thin, 
imbricating plates, those near the margins being much larger and 
thicker than the others. The plates along the rays alternate in 
position, there being about twenty-four or twenty-six pairs. The 
inner ends are diagonally truncated and pointed, so that, where 
undisturbed, they fit together very closely. Where they have been 
displaced, as is the case with most of the arms, they are drawn some- 
what apart, and thus leave alternating openings. 
