1-40 TRANSACTIONS OF THE [mMarR. 17, 
The figure of a thoracic segment given with this species, does 
not correctly represent the actual segment. The ring when 
articulated with adjoining ones shows no furrow; and the pleural 
groove is shallower than represented in the figures. The num- 
ber of segments in the thorax, given as eleven, may not be ex- 
actly that number. 
This species is from the sandstones of Assise 3. 
ELLIPSOCEPHALUS GRANDIS PI. ix., figs. 3 @ to c. 
Trans. Roy. Soc. Can., vol. xi., p. 105, pl. xvii., figs 6 a to ec. 
This is the largest species of its genus known from the Lower 
Cambrian ; it has a short genal spine, and is from the upper part 
of Assise 2. 
ELLIPSOCEPHALUS sp. 
Trans. Roy. Soc. Can., vol. v., p. 129, pl. ii., figs 8 @ to c. 
This, the oldest known species of Ellipsocephalus, is from the 
dark gray sandstones of Assise 1. 
AVALONIA Walcott. 
Under the name of Avalonia, Mr. Walcott has described a 
small trilobite which is evidently related to Ellipsocephalus, but 
which has differences that make it desirable to separate it from 
that genus. The chief differences are the greater proportionate 
size of the glabella, the plaited anterior margin, the weak pos- 
terior margin and the furrow around the fixed cheek. A species 
with these characters occurs with the Protolenus Fauna. 
AVALONIA ACADICA 0. Sp. Pl. ix., fig. 5. 
Head shield semi-circular, rounded down at the sides, and also 
at the front and back. Dorsal suture directly forward to the 
anterior margin and backward, behind the eyelobe, to the pos- 
terior margin. 
Anterior margin of the middle piece of the head shield broad, 
plaited in front. Glabella cylindro-conical, slightly narrower in 
front than at the back; three very faintly marked furrows are 
visible. The occipital furrow is distinct and the ring broad and 
crowned by a low tubercle. The fixed cheeks are rather tumid, 
and at the anterior corner of the glabella, crossed by a shallow 
groove that extends outward to the dorsal suture; there is a 
very faint ocular fillet on the raised part of the fixed cheek. The 
posterior margin and fold are narrow, and the latter is genicu- 
lated at the middle. 
