Figs. 
Figs. 
Figs. 
Figs. 
Figs. 
Figs. 
Figs. 
yey 9G 
i 
bo 
5 
6 
WH ina -@ 
Tand 8 
10 to 13 
14 to 17 
18 to 20 
18 
19 
20 
Zletoure 
21 and 22 
23 
24 to 29 
24 to 26 
27 
28 
29 
PLATE LXVIII. 
IQNEEUGMONON DoyVNGtoONT IO DINGS) AnGeels no so dekdoons SeGnoUMdéo bos G00000BDERS DOGO 
Outline view of the flat side of a specimen preserving the shell with some of the 
surface markings. Ctenodonta bed, Black River group, near Cannon Falls, 
Minnesota. : 
Umbilical side of the same, x2. 
Apertural view of same, x2, showing extremely acute periphery and slightly 
sunken spire. 
Small portion of outer whorl! of figure 1, x5, showing fine regular lines of growth 
of the delicate raised line interrupting their continuity about a third of the 
width of the whorl from the suture. 
Apical side of another example, from the same locality. 
Apertural view of same, x2. The spire is not sunken in this specimen. 
APHIS TONAGER TC EUMON DIEING Ei) lie lien epetererepenepareteietayelekete) olay stelaledcfetetete oeleselais/1=ieleretelalefeler: 
Two views of a specimen retaining some of the shell. Richmond group, 
Richmond, Indiana. 
Small part of the upper side of the last whorl of same, x4, showing curvature 
of the sub-equal striae and the wire-like peripheral edge. The latter forms 
the lower boundary of the figure. 
RYMSSGRNONMAN A THON WeeRGl YS. boacnooouadsescaoneceneo obdoudpodsee veenddneds 
Four views, the last of the natural size, the others <2, of an entire cast, 
apparently of the exterior of the shell. The unusual strength of the 
transverse striae is the most striking of the specific peculiarities of this 
species. Trenton group, Clitambonites bed, Goodhue county, Minnesota. 
IQERISLOM OVA TOD IOSIWN LOMA Ms 5645 co cong onde cago os onbDOD boa G0d0 De GouconeDGdBDKD 
Four views, the first of the natural size, the others 2, of the silicified type of 
this species. The peripheral wrinkles shown in figure 16 may have extended 
all-around originally. Stones River group, Murfreesboro, Tenn. 
IRVADEMSMON GON soyLGECoaOVN SPN BOcaccccccondcnnpeanomobonaaoOnoUD 30000060 cuGROouO 
Umbilical side of a large specimen, the apertural portion restored in the figure. 
Black River group, near Lebanon, Tennessee. 
Upper side of another specimen, from the same locality. 
Apertural view, with the apical whorls restored, of a third specimen, from the 
same locality. 
VASES NO NMGNGARSED HIND © Ui AUT AGO) LIS) Cineperetsttiel tel spelatelteiteteleelelalleietetelate cleisiote ietetetetersiciietolals 
Two views of a coarsely silicified shell of this species. ‘The surface markings 
are very obscure except on a small portion of the upper part of figure 22 
where the denticulations of the periphery also are shown. Black River group, 
Mercer county, Kentucky. 
Dorsal view of a partial cast of the interior from the same locality, showing 
the obscure ridge beneath the peripheral angle. 
TELOSP UAL MIC TACIT SS 15s srt eed aN 3)sscc al cc Se oe ceo aE sd 
Three views of a large and nearly perfect example of this species. Utica group, 
Covington, Kentucky. 
Portion of the under side of same, x5, Showing surface markings and lower part 
of peripheral band. The portion of the latter exposed in this view is very 
narrow. 
Portion of upper side of last whorl of same, x5, showing delicate lines of 
growth, the broad and faintly defined peripheral band, and obscure revolving 
lines on the latter. Such revolving lines often extend over the whole upper 
side of the whorls. 
Peripheral portion of preceding more highly magnified (x10) giving an eee of 
the exceeding delicacy of the markings. 
941 
944 
943 
943 
994 
