Serre N Bers. 
Vol. X. JULY, 1896. No. 3 
ON THE AMERICAN SPECIES OF ERVILIA. 
BY WM. H. DALL. 
Very little attention seems to have been given to the genus Ervi- 
lia, which is composed of small, rather solid shells which are, in the 
recent species, frequently brightly colored, concentrically or radially 
striated or smooth. ‘The soft parts are still unknown though the typ- 
ical species appears to be common in the West Indies, and the largest 
known species is found in British and Mediterranean waters. In the 
forms which are normally concentrically striate or grooved it often 
happens that some of the specimens have the umbonal portion nearly 
smooth, the normal sculpture appearing only when the shell is half 
grown; there are also light modifications of the outline, coming 
within the range of individual variation. In examining the recent 
forms of North America and the West Indies for comparison with 
the fossils, the following were recognized, though the small size of the 
shells and their general similarity of form renders it necessary to 
study them under a magnifier with the greatest care and attention in 
order to grasp the distinctive features. 
Ervilia nitens (Mont.) Turton. 
This species has the valves somewhat compressed, coarsely, 
evenly, concentrically grooved, with faint, radial striations on the 
dorso-posterior surface, both ends somewhat attenuated, the posterior 
longer and more attenuated, the base evenly arched, the anterior 
end shorter, higher, with a steeper dorsal slope; the shell rather 
solid with a robust hinge; the pallial sinus narrow, angular in 
