910 THE PALEONTOLOGY OF MINNESOTA. 
[Conradella bellula. 
We have two specimens of a variety or a closely related species from the Tren- 
ton of Minnesota which we propose provisionally to designate as 
Variety CELLULOSA, 7. var. 
PLATE LXVII, FIGS. 27—29. 
They are both only about 9 mm. in diameter, and differ from the typical form of 
the species in having much less of a keel and in the peculiar modification of the 
surface markings. The lamelle, namely, generally unite with each other in such a 
manner that a cellular rather than striated surface results. When slightly weathered 
the connected sides of the successive loops may appear like delicate longitudinal plates. 
It seems to be a rule that the loops are oblique and joined to each other only on one 
side, the other being open. Again it may appear that the longitudinal line is 
independent and runs directly through the loops. The transverse lamelle are 
unusually crowded, the average on the last volution being from eight to ten in 
2mm. 
The surface markings of C. dyeri have never been correctly illustrated. On the 
accompanying plates we show that the “revolving ridges” are as a rule not ridges 
at all, but only an appearance due to the elevation and longitudinal arrangement 
of the closely following loops of the transverse lamelle. When continuous revolving 
lines are formed it is only through coalescence of one or both sides of the loops of 
succeeding lamelli. 
Compared with the preceding species C. dyeri is distinguished at once by its 
smaller size and unusually crowded surface markings. 
Formation and locality—The typical form occurs in the Richmond group at Richmond and Versailles, 
Indiana; Oxford, Clarksville, Freeport and Waynesville, Ohio; near Maysville, Kentucky, and Spring 
Valley, Minnesota. Variety cellulosa was found in the Clitambonites bed of the Trenton group at St. 
Paul and Cannon Falls, Minnesota. 
Collection. EK. O. Ulrich. 
CoNRADELLA BELLULA, 7. sp. (Ulrich.) 
PLATE LXVII, FIGS. 23—26. 
This species in most respects occupies an intermediate position between C. dyert 
Hall and C. elegans Miller. From the former it is distinguished by its lesser 
thickness (compare figures 24 and 31 on plate LXVIJ) less crowded lamellx, and by 
having numerous well marked lunule on the slit-band. From C, elegans it differs in 
having more slender whorls and less coarsely marked surface. 
