WHITE. ] CARBONIFEROUS FOSSILS. 139 
Genus NATICOPSIS McCoy. 
NATICOPSIS REMEX White. 
Plate 34, fig. 6 a. 
Naticopsis remex White, 1876, Powell’s Rep. Geol. Uinta Mts., p. 109. 
Shell of ordinary size, very oblique when adult, by the elongation 
and enlargement of the last volution; volutions about four, convex, in- 
creasing rapidly in size, the last one large and much produced; spire 
small and short; suture impressed. Surface marked by the usual lines 
of growth, and upon the specimens which are best preserved there are 
very faint indications of the presence of revolving striz also. 
Length across the longest diameter of the volution and the remainder 
of the body volution of an average sized specimen, 23 millimeters; the 
short diameter of the aperture, 17 millimeters. 
Position and locality.—The only known examples of this species were 
obtained by Professor Powell from the middle division of the Carbonif- 
erous series at the confluence of Grand and Green Rivers, Utah. 
Genus MURCHISONIA d’Archiac. 
MURCHISONIA TEREBRA White. 
Plate 34, fig. 4a. 
Murchisonia terebra White, 1879, Bull. U. 8. Geol. Sur. Terr., vol. v, p. 219. 
Shell slender; apical angle 16° or 17°; full number of volutions in 
adult examples, not less than seventeen or eighteen; volutions strongly 
angulated, with only one angle, which is slightly carinated, the carina be- 
finely nodulated or crenulate; the position of the angle much nearer tothe 
proximal than the distal border of the volutions; outer side of the volu- 
tion, between the distal border and the carinated angle, straight, and 
slightly concave between that angle and the proximal border; suture 
slightly impressed, moderately distinct. The whole outer surface of the 
volutions, on both sides of the angle, marked by fine revelving raised 
lines of nearly uniform size, and separated by spaces of about equal 
width with the lines. 
The full length of the largest example would be, if perfect, not less 
than 45 millimeters; width of the last volution, 10 millimeters. 
This species differs conspicuously from any published form of Murchi- 
sonia in the possession of the single prominent angle situated near the 
proximal border of the volutions, and in the broad flattened outer side 
of the volution between the angle and the distal border. It is perhaps 
more nearly related to M. marconiana Geinitz, from the Upper Coal Meas- 
ure limestone of Eastern Nebraska, than to any other published form ; 
but it differs from that species in the more anterior position of the 
revolving angle, in having a more slender spire, and in wanting the 
numerous uniform revolving raised lines which mark the whole outer 
surface of M. terebra. The collections from the Upper Coal Measure 
Strata in the cabinet of the Smithsonian Institution contain some frag- 
ments of an undescribed species of Murchisonia which is closely related 
to ours in general form, and also in having only one prominent carinated. 
revolving angle upon its volutions, the carina being likewise finely nod- 
