24 GEOLOGICAL, SURVEY OF THE TERRITORIES. 
and nearly flat; last one large, widest above and tapering below; su- 
ture shallow, with a slightly impressed line a little below it, around the 
upper margin of each volution; aperture narrow; columella and inner 
lip provided with four very prominent laminze or folds, with sometimes 
one or two smaller ones above these, near the top of the aperture; outer 
lip thin, and strengthened by a few transverse ridges within. Surface 
showing only fine obscure lines of growth and presenting a somewhat 
polished appearance. 
‘“¢ Height of a small specimen 0.43 inch; breadth, about 0.27 inch. 
‘I have only seen very imperfect specimens of this shell, but, taken 
together, they give a correct idea of nearly all of its characters. Some 
of them are three or four times the linear dimensions of that from which 
the above measurements were taken. 
‘Among the specimens from the same locality and bed there are 
some very large broken examples, too imperfect for detailed description, 
that seem to belong to a more elongated species, with a more produced 
spire than that described above. This form, however, as far as its char- 
acters can be made out, appears to agree with the foregoing in nearly all 
other respects. If distinct, it may be called M. elongatus. 
“Locality and position. —Carleton’s coal: -mine, near Coalville, Utah. Cre- 
taceous.” 
After a full examination of all the specimens collected by Mr. Meek, ik 
am inclined to believe them to represent only one species, ‘and that the 
differences which exist are due only to interspecific variation. Figures 
11a and 11), on plate 12, are drawn from the most perfect example dis- 
covered, although it is not more than one-third the size of some individ- 
uals which are represented in the collection by badly broken specimens. 
The four folds upon the inner lip, mentioned by Mr. Meek, vary in 
size and character. The two middle ones are stronger and more promi- 
nent than the other two. The anterior one is narrow and ridge-like, 
and is not so distinctly seen from without as the others are, and it ap- 
pears to be absent in the earlier stages of growth of the shell. The third 
one from the anterior end of the aperture, including the less conspicuous 
one just mentioned, is more transverse in its position than the others, 
and it is also hollowed upon its anterior side and a little flattened upon 
_ its ouver side in shells of fully adult growth. They all rest upon a layer 
of callus, which forms the inner lip, and constitute an unusually con- 
spicuous armature of the aperture. Figure 11d, plate 12, shows this ar- 
mature of a much broken, but very large example, natural size. 
Upon carefully cutting the indurated clay matrix from around the 
spire of several of the specimens of the collection, I find the first volu- 
tion of the minute apex to be reversed; or rather its axis is so turned as 
to have a different direction from that: of the axis of the body of the 
shell. Usually the two axes are nearly at right angles. The reversed 
portion is very minute, and may easily escape detection, even under an 
ordinary lens. Figure lle, plate 12, represents an enlarged view of the 
apex. This isan important feature, and suggests possible relationship of 
this shell to the Pyramidellide, with some members of which family it is 
faunally associated ; but its form, as well as most of its other character- 
istics, are much more like those of the Auriculide. Instead, however, 
of regarding it as a true Melampus, I am more disposed to regard it as 
congeneric with Rhytophorus Meek, the type-species of which is found 
in the Bear River Laramie strata. The longitudinal varices, occupy- 
ing the space immediately in advance of the narrow groove near the 
distal border of the volutions of the type of that genus, were regarded 
as of generic. importance by Mr. Meek, and suggested the name which 
