On Lhigulasma, Etc. — Ulrich. 21 
tually take its place. The more rapid the escape of the gas the 
sooner will the supply be exhausted. The fortunate possessors 
of these wells will do wisely to heed the warning of those who 
have studied the history of gas wells in other localities and 
guard against the wanton waste of their treasure, for there are 
no grounds to support the belief that the supply is inexhausti- 
ble. Indeed, it is probably a question of but a few years till 
Indiana natural gas M'ill be a thing of the past. 
ON LINGULASMA, A NEW GENUS, AND EIGHT NEW 
SPECIES OF LINGULA AND TREMATIS. 
[Continued from the last Number.] 
By E. O. Ulrich. 
TREMATIS FRAGILIS, n sp. 
Fig. 6, 6 a, 6 b. 
Shell large, nearly circular, the width a little greater than 
the length ; substance exceedingly thin. Dorsal valve moder- 
ately convex, with the greatest convexity in the posterior half. 
Umbo small but rather prominent and the beak obtusely 
pointed and not projecting beyond the margin (sub-terminal). 
Cardinal slopes distinctly concave. Surface nearly smooth, 
with faint undulations marking stages of growth and very ob- 
scure concentric lines. Very minute punctures arranged in 
concentric and radial series, occur on and appear restricted to 
the concave slopes on each side of the umbo. Lower or ven- 
tral valve with a very small triangular foramen situated at the 
posterior end of a short but deeply impressed area. From 
the anterior end of this area, the surface rises slowly to a 
point about one-fourth of the length of the shell from the pos- 
terior margin, when it begins to descend and is slightly con- 
cave, in the region between the center of the valve and its 
lateral and front margins. The surface is marked as in the 
upper valve and here the fine punctures occur also for a short 
distance in front of the impressed foramen area. A specimen 
of average size is 24 mm. long, 25 mm. wide, and 4.5 mm. 
deep. 
This species has about the same form as T- ottaicaeiisis 
and T. crassipu7icta,hni the different surface marking will dis- 
tinguish it readily from both. T. punctostriata Hall, has 
coarser puncta, these being also present over the whole surface 
of the dorsal valve. The foramen notch of the ventral valve, 
is also much larger, and the cardinal slopes of the dorsal 
