95 
Sonninia hansoni n. sp. 
Plate XXIII, figures 2, 3 
Diameter 70-5‘mm. 56-0* mm. 
Height of whorl 41-0% 39 -5% 
Thickness of whorl 25-8% 29-1% 
Width, umbilicus 27-8% 30-0% 
‘Without keel 
Except the part showing in the umbilicus, only the core is preserved. 
Living chamber not preserved. As the size of the keel is not known, the 
measurements are given without it. 
A compressed serpenticone. Fairly involute, the inclusion about 
50 per cent. Sublatumbilicate, gradumbilicate. Umbilical margin of 
inner whorls angular, of outer somewhat rounded. Whorl-section com- 
pressed obovate, becoming trigonal on outer whorl, much higher than thick. 
Whorls somewhat flattened on the sides. Venter narrowly rounded, 
becoming eonvexi-fastigate on outer whorl. A hollow (septate) keel of 
unknown size, leaving a smooth partition-band on the core, but neither 
ridge nor sulci. The outer whorl is presumably smooth; the core shows 
no ornament. The whorls in the umbilicus have numerous, straight, 
very fine ribs with just a suspicion of marginal swelling; the ventral 
projection of this ornament, however, is not known. 
The suture-line is complex. The external saddle is deep and rather 
narrow. The first lateral lobe is longer than the external, is rather broad- 
stemmed, rather symmetrical, and the median lobule is longer than the 
two lateral ones. The first lateral saddle is deep and extremely narrow. 
The second lateral saddle is deep and very narrow, but not so deep as the 
first lateral. The inner margin of the suture-line is retracted a little 
and the auxiliary lobes and saddles slant. 
In shape and ribbing this species resembles the European species, 
A. sowerbyi carinodiscus Quenstedt, 1 but is not so compressed and the 
ribbing is even finer. The greatest difference is in the suture-line: for 
Quenstedt’ s species has a much more asymmetrical first lateral lobe, 
a much broader first lateral saddle, and a shorter second lateral lobe. 
Sonninia corrugata Sowerby 2 is also similar, but has somewhat higher 
and thinner whorls, a smaller umbilicus, and a different suture-line, 
including a more narrow-stemmed and asymmetrical first lateral lobe and 
no retraction of the inner part. The first lateral lobe of S. hansoni is 
rather broad-stemmed and symmetrical for a Sonninia, but the surface 
is much worn and the true line may not be recorded. It is placed in 
Sonninia on account of its marked resemblance in form, proportions, 
and ribbing to undoubted species of the genus. 
The species name is given for G. Hanson of the Geological Survey. 
Horizon and Locality. Erom talus of middle sedimentary division 
of the Hazelton group, exposed in a cliff about 1 mile southeast of Silver 
lake, Hudson Bay mountain, B.C. 
Type: Victoria Memorial Museum; holotype, Cat. No. 7707. 
J Anmon. Schwab. Jura, PI. 63, fig. 5 only. 
3 See Buckrnan, S. S.: Type Ammonites, vol. IV, PI. 412 (1923). 
21215 — 7$ 
