Figs. 
Figs. 
Fig. 
Figs. 
Figs. 
Figs. 
Figs. 
toy 34 
land 2 
3 
5and 6 
ll and 12 
13 and 14 
15 to 17 
15 
16 and 17 
18 to 36 
18 and 19 
20 to 22 
23 to 25 
26 to 29 
30 to 36 
PLATE LXX. 
CHUATHROB PIR AN CONTO AW Us an ON Sa eeemanetrce cies tice sana fcieierniiscd scieisreneiccicre 
Basal and dorsal views of a rather small cast of the interior. Trenton group 
(Fusispira bed), near Cannon Falls, Minnesota. 
A testiferous example from the Ctenodonta bed of the Black River group, at 
Chatfield, Minnesota. As usual the surface markings are very imperfectly 
preserved. 
Small portion showing weathered surface markings, and profile outline of last 
whorl, x2, as shown in a specimen from Goodhue county where it was found 
in the Ctenodonta bed. S 
JAMS OSA fey oLinope ys PN 8. onlshing doublod be Sareea Ha ate Ren noe ee ae ann 
View of an incomplete example, preserving the surface markings. Utica group, 
near Graf, Iowa. 
Portion of last whorl of same magnified. 
A cast of the interior from the same locality, doubtfully referred to this species. 
Geological and Natural History Survey of Minnesota, Museum Register No. 
7334. Iu another cast the peripheral band is not flat but almost as distinctly 
concave as on the exterior of the shell. 
EV ORMOTONEAGEB EGIL OTN COyAw Halll lesen Ee restEH asec cieceatics BH eOD CO aoe Sete OOTnEn 
An average cast of the interior of this species, showing that it has a wider apical 
angle and more depressed and, therefore, relatively more numerous volutions 
than H. trentonensis. Clitambonites bed of the Trenton group, Goodhue county, 
Minnesota. 
Another specimen, from the same locality. retaining some of the surface 
markings. The greater part of the last whorl is broken away so as to expose 
(see fig. 17) the filling of the small umbilical perforation. 
Three figures of the var. sublaxa. The first is made up of the apical portion of 
One specimen and the lower whorls of another, and shows the relatively loose 
coiling of the whorls and the resulting obliquity of the sutures which distin- 
guishes this variety from the others. The second figure represents the two 
lower whorls of same, x2, while the third figure represents a portion of another 
specimen also x2. Both of these figures show that the band is considerably 
Wider than in other forms of the species. Trenton formation, Lincoln county, 
issouri. 
Four figures of the var. multivolvis. The first represents an almost entire shell, the 
second and third opposite views of a less perfect example, the fourth an unusu- 
ally small specimen. This variety is distinguished by.its more numerous 
whorls. Richmond group, near Spring Valley, Minnesota. 
Seven figures of specimens which we haye identified with the variety of this 
species which Hall described in 1847 as Murchisonia angustata. Fig. 30 represents 
a weathered example from the Stones River group, at High Bridge, Kentucky. 
The original of fig. 31 is a gutta percha impression of a natural mould in rock 
from an equivalent horizon at Beloit, Wisconsin; that of fig. 32 is from the 
Phylloporina bed of the Black River group near Cannon Falls, Minnesota. Fig. 
33 shows two whorls, x2, of a Black River limestone specimen from Tennessee. 
Figs. 34 and 35 represent opposite views of two specimens from the Utica group 
at Newport, Kentucky, and fig. 36 the lower part of a third specimen from this 
locality. The last shows the form of the apertural notch. 
1006 
1011 
1010 
1012 
1017 
1017 
1014 
