ORDOVICIAN FAUNAS. 181 
LOPHOSPIRA MEDIALIS U. & S. 
Plate XII., Fig. 28. 
1897. Lophospira medias U. & S., Pal. Minn., pt. I1., p. 973, pl. 
73, figs. 23-29. 
Description.—“Height 12 to 22 mm.; apical angle 58° to 70°, the 
average about 63°. Volutions six or seven, all contiguous, somewhat 
depressed, rounded below; upper slope nearly flat, generally a little 
concave in the outer half and gently convex toward the suture, occa- 
sionally convex enough to form an obscure, subsutural angulation ; 
lower carina becoming less distinct with age, never strong, generally 
quite indistinct; between it and the prominent peripheral carina, 
which carries the rounded band, the outline is more or less concave ; 
umbilicus small, but always present. Surface markings rather strong, 
lamellose, strongly curved backward, often gathered into undulating 
groups near the umbilicus.”—UIrich and Scofield. 
LOPHOSPIRA OWENI U. & S. 
Plate XII., Fig. 34. 
1897. Lophospwa owem U. & S., Pal. Minn., pt. II., p. 980, pl. 73, 
figs. 41-45. 
Description.—“Height 25 to 36 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 
umbilicus. The first convexity beneath the peripheral band repre- 
sents the lower carina of L. perangulata and other species, and. in 
young shells it is sharp enough to be called a carina, but as growth 
