96 
Sonninites szlveria, n. sp. 
( Silveria , the Silver Lake country,) 
Plate XXIV, figure 3 
Diameter 
Height of whorl. . . . 
Thickness of whorl, 
Width, umbilicus. . 
100 mm. 32 mm. 
37-3% 37-0% 
20-4% 34-4% 
& o* t'Qyo 
36-5% 37-2% 
■o 
37-0% 
34-4% 
Owing to distortion and imperfection of the specimen, the above 
measurements are only approximate; the keel is included; allowance is 
made for compression of the outer whorl. Chiefly core, very little of test 
preserved. Definitely septate to within 18 mm. of anterior end of outer whorl. 
Inner whorls serpenticonic. Outer whorl compressed serpenticonic 
or platyconic. The umbilicus shallow, latumbilicate. Whorls moder- 
ately embracing, the amount of inclusion about 25 per cent. Venter of 
inner whorls broad, rounded; keel marked on core by a ridge, with small 
furrows on either side; a very small amount of test preserved shows a 
moderately sized hollow (septate) keel. On outer whorl venter narrow, 
rounded; keel marked by a very low ridge on core with very faint furrows on 
either side; a little of test remaining shows a hollow keel of fairly large size, 
without ventral furrows, but with faint lateral furrows. 
On the inner whorls are rather closely set, small ribs of fairly strong 
relief, almost straight on the sides, but bending forward ventrally; the 
total forward curvature cannot be determined, however, for there is not 
enough test preserved to trace the growth-lines on; each rib appears, 
however, to well overlap the next rib. On the anterior part of the second 
last whorl the ribs increase, somewhat irregularly, in size and spacing. 
On the last or outer whorl the ribs decrease in relief and become merely 
broad, low undulations; thus the ornament is approaching smoothness; 
these undulations are almost straight on the side and bend forward as they 
approach the venter, but owing to absence of the test the total forward 
curvature cannot be determined. 
Suture line complex. The external saddle is deeper than wide and 
divided into two branches, the inner of which is the larger. The first 
lateral saddle is deep and very narrow. The first lateral lobe is longer 
than the external, has a rather broad stem and three branches or lobules, 
the centre of which is longer than the two lateral; it is almost symmetrical. 
It has only been possible to prepare a little of the second lateral lobe. 
It is about two-thirds as long as the first lateral lobe. A preparation 
of the suture-line on an inner whorl shows a deep, second lateral saddle 
and an inclined auxiliary lobe. The inner edge is not dependent, however. 
This species is very similar to Sonninites alsaticus (Haug), 1 but is 
smaller and has finer, more regular, and more closely spaced ribs on the inner 
whorls. Dorsetensia lennieri Brasil 2 has much thinner whorls, fewer and 
more widely spaced ribs, a non-septate keel, and deeper ventral furrows. 3 
t Horizon and Locality. From the talus of the 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. 7708. 
[ See Buckman, 8. S.:_Type Ammonites, voI.VI, PIb.528, 528A (1925). 
