85 
arrangement, some of the shells referred by Hall to Meristed/a will be considered here under 
the head of Spirigera, whilst others will come under Athyris. 
The species of Spirigera, as here understood, which have come under my notice in the 
Devonian Rocks of Ontario, are three in number, viz. : WS. spiriferoides (= S. concentrica ?), S. 
scitula, and S. rostrata. 
102, SprRIGERA SPIRIFEROIDES (Haton). 
Terebratula spiriferoides (Katon), American Jowwnal of Science, Vol XXI., p. 137. 
Atrypa concentrica (Conrad), Annual Report on Pal. New York, p. 111. 
Atrypa concentrica (Hall), Report Fourth Dist., New York, p. 198, Fig. 5. 
Spirigera spiriferoides (Hall), Tenth Report on the State Cabingt, p. 153. 
Spirigera concentrica (Billings), Canadian Journal, New Series, Vol. VI., p. 145, Figs. 52, 
and 54-57. 
A thyris spiriferoides (Hall), Pal. New York, Vol. 1V. Plate XLVI, Figs. 5-31. 
eee Spirigera (Athyris) concentrica of Kuropean paleontologists}. 
hell transversely sub-oval, sub-orbicular, or sub-quadrate, with its greatest width near 
the middle, slightly truncated anteriorly, or more commonly having the front margin pro- 
duced into a tongue-shaped rounded projection. Hinge-line very short, the cardinal extremi- 
ties rounded off. Both valyes convex, but not excessively so ; the ventral valve with a shallow 
mesial sinus which dies out towards the beak ; the dorsal valve with a corresponding mesial 
fold. The beak of the ventral valve incurved, and perforated by a small but conspicuous 
foramen. Dorsal valve more convex than the ventral, with a small rounded beak which is 
concealed beneath that of the ventral valve. Surface?marked by close-set concentric lines of 
growth, which are often produced into imbricated thin lamell, and which are always more 
crowded towards the front margin of the shell. 
The interior of the ventral valve exhibits two strong dental lamelle, extending to the 
base of the rostral cavity, where the muscular impressions commence, The interior of the 
dorsal valve exhibits a strong cardinal process, with elevated socket-margins behind, and a 
narrow elliptical muscular impression which is ‘“ divided by a low median crest” (Hall). The 
spires show. about fifteen turns each. 
Whether Spirigera spiriferoides (Katon) is identical with Spirigera (Athyris) concentrica 
(Bronn,) from the Devonian Rocks of Europe or not, is a question which I have no means of 
deciding, not having at present access to authentic specimens of the latter. I should, however, 
be strongly inclined to think that the two forms, as believed by De Verneuil, Sharpe, Billings, 
and others, are in reality identical ; though, in deference to the views of Professor Hall, I 
have retained our form as a separate species. In any case, even supposing the two to be the 
same, the name of spiriferoides will have to be retained, as having the priority over that of 
concentrica. 
S. spiriferoides is of rare occurrence in the Corniferous Limestone, but is found commonly 
in the Hamilton group. Our specimens present no special peculiarity except that, without 
exception, so far as I have seen, they are smaller than those from the same formations in the 
State of New York. Thus, the largest specimen in our collection has only a width of nine 
lines, and a length of eight lines ; whereas specimens from New York sometimes have a width 
of nearly an inch and three-quarters, and a length of an inch and a half or more. 
Locality and Formation.—Corniferous Limestone, Hagersville ; Hamilton Group, Widder, 
and Bartlett's Mills near Arkona, in the Township of Bosanquet. 
103. SPIRIGERA ROSTRATA (Hall). 
Atrypa rostrata (Hall), Report on the Fourth Geol. Dist. New York, p. 202, Fig. 3. 
Athyris (2) rostrata (Billings), Canadian Journal, New Series, Vol. V., p. 281, Figs. 
4 
Meristella rostrata (Hall), Pal. New York, Vol. IV., Plate L, Figs. 13-17. 
Shell small, ovate or sub-trigonal, sometimes sub-attenuate above. Both valves convex, 
the ventral scarcely more so than the dorsal. Ventral valve most convex above the middle, 
usually with a shallow rounded mesial sinus in front, which, however, is sometimes almost 
obsolete; the beak prominent, incurved over that of the dorsal valve, but not in contact with 
it, and perforated by a conspicuous foramen. Dorsal valve regularly convex, sometimes with 
