NIAGARA GROUP. 
285 
The only specimen seen is imperfect at the anterior extremity, the posterior extremity and 
beak alone remaining. 
Fig. 6 a. The shell, natural size. 
Fig. 6 b. A portion of the surface enlarged. 
Position and locality. In the shale of this group at Lockport. 
474. 19. MODIOLOPSIS StJBALATUST 
Pl. LIX. Fig. 7. 
Compare M. subalatus , page 84 of this volume, pl. 17, figs. 5 and 6. 
Obovate, the posterior extremity rounded, and broader than the anterior extremity; umbo 
slightly prominent, and elevated above the cardinal line ; surface marked by fine concentric 
strise. 
This is apparently a large individual of M. subalatus of the Clinton group. It differs from 
the other species of this genus in the narrow anterior extremity being proportionally more 
extended, with little evidence of the strong muscular impression. 
Position and locality. In the shale of this group at Wolcott. 
478. 4. ORTHONOTA CURTA1 
Pl. LIX. Fig’. 8. 
Reference 0. curta, p. 86 of this volume, pl. 17, fig. 11. 
A fragment of slate, presenting a cardinal view of the two valves of a species of Orthonota. 
From the condition of the specimen, it is impossible to determine any difference between it 
and the species of the Clinton group. 
Position and locality. In the shale of the group at Wolcott. 
