414 : BULLETIN OF THE NATURAL HISTORY SOCIETY. 
within the margin. Eyes submedian [near the mid-length of the 
shield], small. Pygidial axis long, somewhat prominent at the apex. 
Tt is three inches long and one and a half broad.” 
The addition to this description in Salter’s trilobites is as follows : 
“The head is more than a third of the whole length, and longer 
than the thorax, which in its turn, is longer"^ than the caudal shield. 
The head is semi-oval, rather pointed in front, and has mry short pos- 
terior spines ; it is broadly depressed around the margin. The gla- 
bella portion is scarcely marked out ; the eyes are placed nearly half- 
way up the head ; they are small (two lines long), the facial sutures 
curving out boldly beneath them, and cutting the posterior margin 
more than half way out from the axis. 
Above the eye they form a narrow ogive, and nearly follow the 
front margin. On the underside of the head the vertical furrow on 
the epistome shows distinctly through the cast. The labrum [hypos- 
tome] is imperfect, but exhibits a strong marginal groove, and two 
small lateral furrows. 
The body rings have the axis as broad as the sides, and moder- 
ately convex. The pleune are flat as far as the fulcrum, truncate at 
their ends, and have but a slight groove, which reaches two-thirds 
of the length. The fulcrum is at one-third in front, and less than half 
way out in the middle pleune. 
The caudal axis extends three-fourths down the smooth tail, very 
indistinctly marked above, but in some specimens crossed by several 
faint rings, and is always prominent at the tip.” 
The Cape Breton form, by its hypostome, is clearl}^ within Calla- 
way’s genus Asaphellus. Allowing for the distortion of the type 
species, figured by Salter, it is quite as large. 
Certain features, not mentioned by Salter, are characteristic of the 
Cape Breton form. The glabella is somewhat ridged along the axial 
line, and its margins more distinct. About one-fifth of the length of 
the head shield from the back there is a slight but distant prominence 
(scarcely a tubercle) on the axial line ; a fairly marked tubercle is also 
found on the median line of the axis of the pygidium, at the back of 
the first ring, and faint traces of similar prominences on succeeding 
rings. 
=*= Tlie italics are inserted to mark points of difference from the Canadian variety. 
