25 
thicker than high, and more rounded. Lappet, partly preserved, is lateral 
in position. The number of primary ribs per whorl slowly increases on 
the inner whorls, the number on the ultimate whorl is not known. On 
the inner whorls there are about three secondaries to each primary con- 
sisting chiefly of two bifurcated and one intercalated or rarely three trifur- 
cated secondary ribs. On the anterior part of the ultimate whorl there 
are two secondary ribs to each primary, arising by furcation. The ribs 
have considerable relief. The suture line is similar to that of K. crickmayi 
n. sp. LI is about symmetrical; the median lobule is fairly long and nar- 
row. The proportional whorl height is somewhat greater than in K. 
crickmayi , K. mackenzii , and K. canadensis. The umbilicus is a little 
smaller than that of K. crickmayi or of K. mackenzii. The primary ribs 
per w’horl are intermediate in number between those of K. crickmayi and 
K. mackenzii. The whorl proportions are somewhat as in Otoites delicatus 
S. Buckman 1 , but the umbilicus is larger and the ribs per whorl fewer. 
Horizon and Locality. In the lower part of the Yakoun formation 
at Mackenzie bay, on the north side of Maude island. 
Type. National Museum of Canada, Ottawa; holotype, Cat. No. 
9018. 
Kanastephanus canadensis n. sp. 
Plate XV, figures 4, 5 
Diameter 
Height, whorl 
57-5 
57-0 
55-2 
29-2 
41-2 
48-6 
52-0 
29-2 
44-2 
47-5 
50-0 
27*0 
47*8 
45*2 
48*0 
26*3 
49*0 
45*4 
45*0 
27*1 
51*4 
44*3 
Thickness, whorl 
39-2 
390 
Width, umbilicus 
Primary ribs 
23 
49 
Secondary ribs 
Perlatumbilicate, the umbilicus increasing with growth of ultimate 
whorl. Whorl suture on inner whorls is at outer edge of tubercles, but 
near beginning of living chamber it moves outward, enlarging the umbilicus. 
Whorl section depressed on inner whorls, but less so on ultimate whorl, 
where the proportional thickness decreases and the venter becomes more 
arched. The living chamber is nearly three-fourths of a whorl; the last 
septum is at a diameter of 44-5 mm. The ribs have considerable relief, 
and are straight across the venter. On the anterior part of the penultimate 
w'horl there are about 3 secondary ribs to each primary, arising chiefly by 
bifurcation and intercalation; on the first quarter of the ultimate whorl 
there are two bifurcated secondary ribs to each primary and one inter- 
calated for every second primary rib; on the anterior three-fourths of the 
ultimate whorl there are on the average two bifurcated secondary ribs to 
each primary, plus an additional rare intercalated secondary rib. The 
same ribs are not joined together on opposite sides. The suture line is not 
well prepared but is similar to that of K. crickmayi and K. altus. LI is 
tripartite and is nearly symmetrical. L2 is small and the tubercle is on it. 
This is the largest of the species of Kanastephanus in the Yakoun 
formation and has proportionately the thickest ultimate whorl. In number 
of both primary and secondary ribs it resembles whorls of K. crickmayi 
iType Ammonites, III, pt. 20, PI. 151 (1919). 
