82 
general a smaller species than the former. I have only seen a few detached valves of this specie? 
in the Corniferous Limestone. 
Locality and Formation.—Corniferous Limestone of Port Colborne and Hagersville. 
98. SPIRIFERA DUODENARIA (tiall). 
Delthyris duodenaria (Hall), Geol. Report, 4th Dist., New York, p. 171. 
Spirifer duodenaria (Hall), Catalogue in Report on State Cabinet. 
Spirifera duodenaria (Billings), Canadian Journal, New Series, Vol. VI., p. 256, Figs. 
65-67. 
Spirifera duodenaria (Hall), Pal. New York, Vol,, IV., p. 189, Plate XXVII., Figs. 
13-16 ; Plate XXVIII. Figs. 24-33. 
Shell semi-circular, or sub-triangular, the hinge-line equal to the greatest width of the 
shell; the cardinal angles rounded or acute, rarely pointed. Ventral valve slightly more convex 
than the dorsal, depressed towards the cardinal extremites, with a prominent beak, a narrow 
area, and a mesial sinus of moderate width and depth. Dorsal valve moderately convex, 
with a narrow and prominent mesial fold corresponding with the ventral sinus, its area linear. 
Surface exhibiting six or seven strong rounded simple ribs on each side of the mesial fold and 
sinus. The ribs are broad and are separated by rounded intervals, and they decrease in size in 
proceeding from the middle line towards the cardinal extremities. 
Most examples show a completely smooth surface; but the shell, in perfect examples, is 
marked by “lamellose concentric strie, giving a papillose or sub-fimbriated aspect at their 
junction.” (Hall). 
Spirifera duodenaria is not uncommon in the Corniferous Limestone of Western Ontario, 
and is usually readily recognised by its large rounded ribs and generally smooth surface. It 
varies a good deal in its dimensions, average specimens having a width of eight or ten lines 
along the hinge-line, and a length of five or six lines. 
Locality and Formation.—Corniferous Limestone of Port Colborne, Ridgeway, Hagers- 
ville, &e. 
99. SprriFERA RARICOSTA (Conrad). 
Delthyris raricosta (Conrad). Jour. Acad. Nat. Sci. of Philadelphia, Vol. VIII., p 262, 
Pl. 14, Fig. 18. 
Delthyris undulatus (Vanuxem), Geol. Report, Third Dist. New York, p. 132, Fig. 3. 
Spirifera raricosta (Billings), Canadian Journal, New Series, Vol. VI., p. 258, Figs. 
71-73. 
Spirifera raricosta (Hall), Pal. VW. Y., Vol. IV., Pl. XXVIL., Figs. 30-34, Pl. XXX., 
Figs. 1-9. 
" Having only obtained a few imperfect specimens of this fine species, I shall content my- 
self with simply noting its existence, without giving its description. 
Spirifera raricosta is at once distinguished from the other Spirifere of the Corniferous 
Limestone by its possession of from two to four strong, prominent, rounded or sub-angular 
plications on each side of the mesial fold and sinus. The ventral valve also is very gibbous 
above, and the beak much elevated, whilst the cardinal angles are rounded. 
Locality and Formation.—Rare in the Corniferous Limestone of Port Colborne. 
100, SPrRIFERA FIMBRIATA (Conrad). 
Delthyris fimbriata (Conrad), Journ. Acad. Nat. Sci. of Philadelphia, Vol. VIIL., p. 263. 
Spirifera fimbriata (Billings), Canadian Journal, New Series, Vol. VI., p» 257, Figs. 
68-70. 
Spirifera fimbriata (Hall), Pal. N. Y., Vol. IV., Pl. XXXIIL., Figs. 1-21. 
Shell transversely oval, bi-convex, the hinge-line shorter than the greatest width of the 
shell, and the cardinal angles rounded and not produced. Ventral valve gibbous in the upper 
half, the beak:small but prominent, incurved over the area, the latter being high and concave. 
The sinus is well-defined, sometimes rounded sometimes angular, and extending from the 
beak to the front of the shell, with a variable number (usually three or four, but sometimes 
eight or nine) of low and obscure plications on each side. Dorsal valve moderately gibbous, 
