360 
PALEONTOLOGY OF NEW YORK. 
tion. These are more or less irregular or sinuous, elevated at the concentric 
varices and crossed by faint concentric lines. 
The typical example has a length of 21 mm. and a width on the hinge of 
24 mm. 
Niagara group. Louisville, Kentucky. 
Plectambonites producta, sp. nov. 
PLATE LXXXIV, FIGS. 23, 21. 25. 
The original of this species is an internal cast of the pedicle-valve, with 
short, straight hinge; rather narrow, depressed umbo, the shell becoming highly 
convex and greatly produced anteriorly. The sides of the valve are. somewhat 
appressed medially and the anterior margin slightly expanded and suboval in 
outline. The cast shows the impression of short, divergent dental plates and a 
moderately broad muscular impression. The width of the shell on the hinge is 
10 mm.; its length, 23 mm.; its convexity from the posterior margin, 8 mm.; 
from the anterior margin, 28 mm. 
Niagara dolomites. Yellow Springs, Ohio. 
Spirifer crispatus, sp. nov. 
PLATE XXXVI, FIGS. 9, 10. 
Shell small, with moderately high, incurved area, scarcely extended on the 
hinge; well-developed median fold and sinus, and three coarse plications on 
each lateral slope. The surface is covered by conspicuous concentric lamellae. 
Niagara group. Maryland. 
Spirifer CANANDAiGUiE, sp. nov. 
PLATE XXXVII, FIGS. 23, 24, 25. 
Shells of rather small size, having somewhat the aspect of an elongate and 
umbonate S. fimhnatus. Umbo of pedicle-valve prominent, narrow and closely 
incurved at the apex. Hinge-line quite short, cardinal area small, incurved, 
Median sinus deep, produced on the anterior margin, its anterior width being 
