82 



general a smaller species than the former. I have only seen a few detached valves of this species 

 in the Coi niferous Limestone. 



Locality and Formation. Corniferous Limestone of Port Colborne and Hagersville. 



98. SPIRIFERA DUODENARIA (tiall). 



Delthyris duodenaria (Hall), Geol. Eeport, 4th Dist., New York, p. 171. 



Spirifer duodenaria (Hall), Catalogue in Eeport on State Cabinet. 



Spin/era, duodenaria (Billings), Canadian Journal, New Series, Vol. VI., p. 256, Figs. 

 65-67. 



Spirifera duodenaria (Hall), Pal. New York, Vol, 3 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 strife, 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, &c. 



99. SPIRIFERA RARICOSTA (Conrad). 



Delthyris raricosta (Conrad). Jour. Acad. Nat. Sci. of Philadelphia, Vol. VIII., p 262, 

 PI. 14, Fig. 18. 



Delthyris undulatus (Vanuxem), Geol. Report, Third Dist. Neiv York, p. 132, Fig. 3. 



Spirifera raricosta (Billings), Canadian Journal, New Series, Vol. VI., p. 258, Figs. 

 71-73. 



Spirifera raricosta (Hall), Pal. N. Y., Vol. IV., PI. XXVII., Figs, 30-34, PI. 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 Spiriferce 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. SPIRIFERA FIMBRIATA (Conrad). 



Delthyris jimbriata (Conrad), Journ.Acad. Nat. Sci. of Philadelphia, Vol. VIII., p. 263. 



Spirifera fimlriafa (Billings), Canadian Journal, New Series, Vol. VI., p. 257, Figs. 

 68-70. 



Spirifera fimlriata (Hall), Pal. N. Y., Vol. IV., PI. XXXIII., 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 heak 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, 



