TEREBRATULIDJE OE THE HAMILTON SHALES. 
389 
Young specimens, which I refer to this species, are more gibbous than 
the older ones. The larger specimens are from six-eighths to seven- 
eighths of an inch long and five-eighths of an inch wide. 
This species is proportionally wider and with more extended beak than the 
T. sullivanti, and more regularly arcuate from beak to base of the ventral valve : 
it is, moreover, not emargiuate in front. It appears to be a well-marked species, 
and, in its larger individuals, will be readily distinguished. 
Geological formation and localities. From the limestone of the Falls of the 
Ohio (sent to me by Dr. James Knapp of Louisville, Kentucky) ; and also from 
the Corniferous limestone of Canada West : collected by Mr. De Cew. 
Teretoratula rceiiiingeri. 
PLATE LX. 
Terebratula rczmingeri : Hall, Sixteenth Report on the State Cabinet, p. 48. 1863. 
Shell ovate, more or less gibbous, truncate or slightly sinuate in front. 
Ventral valve gibbous above the middle; umbo gibbous, inflated ; beak 
prominent, incurved over the opposite beak, and truncated by a round 
foramen which is often mainly anterior to the apex, and completed 
on the lower side by two deltidial plates : cardinal slopes rounded, 
often depressed in the middle towards the front. 
Dorsal valve extremely gibbous, little longer than wide; the greatest 
convexity at the middle or above. 
Surface marked by fine concentric striae which are often crowded into 
prominent wrinkles towards the front. Shell-structure finely punctate. 
.The interior shows a short terebratuliform loop, which is abruptly 
recurved at its lower extremities. 
This species was first indicated from specimens sent by Dr. Rceminger, from 
Thunder bay, Michigan ; but it has since proved of common occurrence in New. 
York. The Michigan specimens are usually more gibbous and distinctly depressed 
or sinuate in front; while that character, though present in some of the eastern 
specimens, is not constant. There is, however, no difficulty in recognizing the 
characters of the species in any well-preserved specimens. 
This species is the smallest of the genus, or of the family, known as occurring 
in the Hamilton shales of New-York. 
