24 
The cone shape is a cadicone becoming serpenticone. Perlatumbilicate, 
the umbilicus increasing with size, but not uniformly. On inner whorls, 
the whorl suture is just on the outer edge of the tubercles, but in living 
chamber part and on last three-fourths of ultimate whorl, the whorl suture 
leaves the line of tubercles and migrates outward. The whorl section is 
depressed, being much thicker than high. On the ultimate whorl the 
proportional thickness decreases, whereas the proportional height changes 
very little, but the section remains thicker than high; the section also 
becomes more rounded. The living chamber is nearly three-fourths of 
the ultimate whorl. The lappet is relatively short and lateral in position. 
The primary ribs are fairly numerous, are very little inclined, and each 
ends in a tubercle. On the ultimate whorl there are two bifurcated 
secondary ribs to each primary and there are very rare single intercalated 
ribs. On inner whorls the number of secondary per primary ribs is greater. 
All ribs have considerable relief, are narrow and fairly sharp. A good 
preparation of the suture line could not be obtained. There is a large ES, 
deeper than wide. 
This species agrees with Kanastephanus crickmayi n. sp. in general 
proportions and in number of secondary ribs, but it has many more primary 
ribs and sharper and more pronounced ribs on the anterior part of the 
ultimate whorl. Stephanoceras sp. of Boehm 1 has about the same number 
of primary ribs and a few more secondary ribs per whorl, but has not the 
rapid change from cadicone to serpenticone. The lappet and suture line 
of Boehm’s species are not illustrated, so that comparison of these features 
cannot be made. 
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. 
9017. 
Kanastephanus altus n. sp. 
(altus, high) 
Plate XVI, figures 4-6 
Diameter 
47 -0 2 
33-1 
32-0 
28-8 
25-0 
22-3 
Height, whorl 
32 -4 2 
35-2 
360 
35-7 
33-7 
33-6 
Thickness, whorl 
47.42 
59-5 
60-0 
60-8 
62-3 
61-7 
Width, umbilicus 
46 -6 2 
40-9 
40-2 
41-3 
43-2 
43-0 
Primary ribs 
18* 
The inner whorls and the anterior and posterior parts of the ultimate 
whorl are preserved. Latumbilicate to perlatumbilicate, the umbilicus 
decreasing a little on the penultimate and increasing on the ultimate 
whorl. The whorl suture on the inner whorls is on the outer edge of the 
tubercles, but on the ultimate whorl is considerably outside the tubercles. 
The inner whorls are depressed, are much thicker than high, and somewhat 
flattened or broadly arched on the venter. The penultimate whorl is 
increasing in height, but varying little in thickness. Ultimate whorl 
decreases in thickness, less so in height, becomes less depressed, although 
1 Boehm, G.: Nova Guinea Kesultats L’Expedition scientifique Ne’erlandaise & la Nouvelle Guin6e en 1903, 
vol. 6, Geologie, Absehnitt I, p. 10, PI. 5, fig. 4 (1912). 
1 Approximate. 
