57 
Costae, strong, strongest on venter, bent forward, but not strongly, in 
crossing venter, strongly reflexed in crossing umbilical border. At 30 
mm. diameter there are eight primaries and twelve secondaries in a quad- 
rant. Resembles C. grewingki in form and rib-curve, but differs in its 
more closely crowded ribs. Only immature specimens were found. 
Dimensions. See graph. 
Locality. Zone of Cadoceras hrooksi, on Deer creek one-quarter mile 
from its mouth; also other places. 
Cadoceras schmidti Pompeckj 1900 
Figure 3 
1900. Pompeckj : Verhandl. Kais. Russ. Min. Gesell. St. Petersburg, 
2 te Ser., Bd. XXXVIII. 
Somewhat similar to the last, but having a much narrower umbilicus 
and costae bent strongly forward in crossing the venter. At 30 mm. dia- 
meter there are eight primaries and fourteen secondaries in a quadrant. 
This species like the last has the costae strongly reflexed in crossing the 
umbilical border. 
Dimensions. See graph. 
Locality. Zone of Cadoceras hrooksi, on Deer creek, one-quarter mile 
from the mouth; also other places. 
Cadoceras hrooksi sp. nov. 
Plate XVI, figures 3, 4, 5; Figure 3 
Inner whorls rounder in cross-section than is usual in this genus. 
Cadicone is attained at about 38 mm. diameter, so possibly a large size is 
never reached. Costae, obtuse, very slightly bent forward in crossing 
venter, and slightly reflexed in crossing umbilical border. Table showing 
number of ribs in a quadrant of whorl at various stages. 
Diameter 
30 mm. 8 primaries 13 secondaries 
50 “ primaries obsolete, 13 “ 
8 butlse on umbilical 
“keel” 
Locality. Zone of Cadoceras hrooksi, on Deer creek, one-quarter mile 
from its mouth, west side of Harrison lake. 
Name. After Mr. Allan Brooks, in recognition of his inimitable pic- 
torial contributions to natural history. 
Genus, Anacardioceras Buckman 1923 
This stock has not previously been reported from North America, but 
it seems likely that it is represented by some of the species of ‘‘Cardio- 
ceras** described from Wyoming and Alaska. The form from Harrison 
lake, described in the sequel, differs from the typical British species in its 
perfect smoothness, venter of persistently knife-edge sharpness, and 
