268 ROYAL SOCIETY OF CANADA 
convex than the dorsal ; on the average it is three times more convex, but 
the relative convexity is variable. The edge of the orifice of the shell on 
this side is slightly bowed upward in the middle, and near each end is a 
sinus where the growth line curves upwards before crossing over to the 
dorsal side, hence the rising arch of the edge on the dorsal side belongs 
partly to the ventral side. 
The angles between the dorsal and ventral sides are sharp, especially 
in the apical half of the shell. The lip on the dorsal side is strongly 
arched upward, and the surface striæ correspondingly curved. 
Sculpture—On both sides are distinct transverse striæ, but no longi- 
tudinal striæ. ‘The inner surface of the shell is smooth and does not show 
growth lines. 
Size of the tube. Width at the aperture 14 mm. Shorter diameter 
at aperture8 mm. Length of tube supposed to be about 50 mm. or more. 
The lip projects above the tube about 5 mm. 
Locality—Found with the preceding. 
HOLASAPHUS, n. gen. 
Among the fossils from McFee’s Brook was a trilobite related to 
Asaphus, but different from any described genus. From Bathyurus, Bill, 
it is excluded by the shallowness of the furrows on the head-shield, and 
the low relief of the glabella ; it is shut out of Bathyurellus, Bill., by the 
narrow marginal fold and long axis of the pygidium ; from Protypus, 
Walc., by its shorter glabella, inclined to conical, and the prolonged 
angles of the free cheeks ; from Asaphiscus, Meek, by its Megalaspis-like 
pygidium ; from Asaphelina, Mun-Cham. and J. Berg., by having only 
one spine to the pygidium; from Platypeltis, Call., by its shorter, 
cylindro-conical glabella, and markedly segmented and lobed pygidium. 
HoLASAPHUS CENTROPYGE, n. sp., Pl. IL, figs. 4a and b. 
Middle piece of the head sub-quadrate. Anterior margin with a dis- 
_ tinct fold. Glabella sub-cylindrical, rounded in front, about one-quarter 
longer than wide, not furrowed. Occipital ring narrow, divided from the 
glabella by a narrow fold, and having an obscure tubercle at the back on 
the median line. Fixed cheeks slightly wider at the middle than half of 
the width of the glabella, widening before and behind the eyelobe, meet- 
ing in front of the glabelia, furnished with short, prominent eyelobes, no 
ocular fillet. Posterior furrow and fold narrow, the former shallow. 
Pygidium large sub-triangular, bordered all around, furnished behind 
with a sharp spine about one-third of its length. The axis is prominent 
and has three distinct rings and three obscure ones at the back of these ; 
each of the front rings is furnished with a small tubercle at the back 
edge. The side lobes of the pygidium have four costæ and sometimes a 
