980 THE PALEONTOLOGY OF MINNESOTA. 



[Lophosplra owenl. 



is sharply angular. The basal part of the last turn is decidedly ventricose, turning 

 more or less abruptly into the deep though small umbilicus. On the flattened and 

 nearly vertical sides, about midway between the peripheral angle and the basal 

 outline, a faintly raised line (lower carina) is usually distinguishable. The suture 

 is deep and the upper edge of the last whorl is flattened, and forms a shoulder-like 

 prominence, between which and the peripheral angle the surface is strongly concave. 

 Aperture obliquely subquadrate, rounded below. Surface markings only in rare 

 cases leaving any traces upon the casts, consisting on the shell itself of lamellar 

 lines of growth, .5 to 1.0 mm. apart, with much finer lines between them. They 

 curve rather strongly backward from above and below to the peripheral angle. 



Compared with species described in this report, L. conradana is distinguished 

 by its strongly ventricose base. The general appearance of the shell might be 

 considered to indicate close affinities with L. bicinda and L. obliqua, but the character 

 and strong retral curve of the lines of growth prove that the species belongs to the 

 L. perangulata section of the genus. 



The Wisconsin specimen figured by Prof. Whitfield (loc. cit.) looks like an 

 unusually large example of L. conradana that has been shortened by pressure, 

 causing the apical angle to be abnormally wide. Still, the angle in the figure is 

 only about 68, while in his description Prof. Whitfield gives it at "about ninety 

 degrees." Whatever the specimens described by him may turn out to be, we are 

 satisfied that they are distinct from L. ventricosa Hall sp. In a more recent publi- 

 cation* Prof. Whitfield expresses himself as though he had arrived at a similar 

 conclusion. 



Formation and locality. A. frequent fossil of the Vanuxemia bed of the Stones River group at 

 Minneapolis and St. Paul, Minnesota; occurs also, though rarely, in equivalent strata at Beloit, Wisconsin. 



Colkctions. Geological and Natural History Survey of Minnesota; E. O. Ulrich. 

 Museum Register, No. 5036. 



LOPHOSPIEA OWENI, . Sp. 

 PLATE LXXIII, PIGS. 41-45. 



Hight, of Black River specimens, 25 to 36 mm., of Utica specimens, 18 to 27 mm.; 

 apical angle 59 to 62. Volutions six or seven, the first very minute, decidedly 

 angular. Peripheral band prominent, thick and rounded, sometimes margined by a 

 delicate line on each side. Upper slope concave, except near the suture where 

 there is usually a broad rounded ridge or carina; this ridge, however, becomes quite 

 obsolete on the sixth or seventh volution. Lower side sloping inward, scarcely 

 ventricose, the outline being first concave, next convex, then straight or concave 

 and finally convex again, there being a peculiar swelling just behind the minute 



* Bull. Amur. Mus. Nat. Hist., vol. 1, no. 8, p. 813, 1886. 



