18 
One has a suture line with very deep saddles like Defonticeras ? sp., but it is 
larger and has thicker whorls. 
Horizon and Locality. In the lower Yakoun at Richardson bay, 
south side of Maude island. 
Type. National Museum of Canada, Ottawa; Cat. No. 9014. 
Frogdenites ? cf. profectus S. Buckman 
Plate XII, figure 6 
Cf. 1923. Frogdenites profectus S. Buckman, Type Ammonites, V, pt. 42, 
PI. 430. 
Mr. Buckman advises the above designation of one of the specimens 
in the Defonticeras fauna, noting in comparison with D. marchandi, the 
flatter periphery and sharper fall of the sides into the umbilical area. 
It differs from F. profectus chiefly in the anterior ribs which do not become 
widely spaced. As only a part of the ultimate whorl and none of the inner 
whorls are preserved, the exact affinites of this form cannot be determined. 
Horizon and Locality. In the lower Yakoun formation at Richardson 
bay, south side of Maude island. 
Type. National Museum of Canada, Ottawa; Cat. No. 9015. 
Family, stepheoceratidae S. Buckman 
Genus, Zemistephanus McLearn 
1927. Zemistephanus McLearn, Trans. Roy. Soc., Canada, 3rd ser., 
vol. 21, sec. IV, p. 72. 
The inner whorls are cadiconic and latumbilicate. On ultimate 
whorl becoming serpenticonic, there being umbilical enlargement and 
whorl contraction, particularly in the proportional thickness of whorl. 
The primary ribs end in tubercles and are becoming less prominent on the 
ultimate whorl, but persist to the end. The suture line is moderately 
complex; E8 is large and deeply divided, SI is smaller than ES, and S2 is 
shallower than, and as broad as, SI; LI is somewhat longer than EL, L2 is 
much smaller than LI, is simple and cruciform, has a long, median lobule 
and is a little inclined; the auxiliary lobes are inclined. The tubercle 
is about on the border between L2 and S2. The genotype is Ammonites 
richardsoni Whiteaves. 
The cone shape recalls Emileia (of Sonninian age) in the cadicone 
stage, i.e., E. crater S. Buckman 1 ; there are tubercles at the ends of the 
primary ribs, however, and the suture line is not so complex as in typical 
Emileia S. Buckman. The cone shape also recalls Tulites S. Buckman, 
but the ornament is stronger and the suture is somewhat more complex 
and differs in detail, L2 being simple, not double, and cruciform. There 
is some resemblance in shape, ribbing, and suture line to Teloceras, e.g., 
T. banksii (J. Sowerby), 2 but the tubercle is more dorsal in position with 
respect to L2 of the suture line and there is the falling off to serpenticone, 
which does not occur in Teloceras. Stephanoceras ? humphriesi crassicostata 
Quenstedt, as identified by Boehm 3 from New Guinea has a similar cone 
1 Type Ammonites, III, pt. 22, PI. 164 (1920). Yorkshire Type Ammonites, II, p. IX (1913). 
2 Type Ammonites, VI, pt. 59, PI. 660B (1928). 
3 Boehm, G.: Unteres Callovien und Coronatenschichten zwischen MacCIuer-Golf und Geelvink bai, Nova 
Guinea. Resultats L’eip6dition scientifique Ne’erlandaise A la NouveIle-Guin6e en 1903, vol. 6, Geologie, 
Abschnitt i, PI. 3, fig. 2. 
