26 TRANSACTIONS OF THE ROYAL CANADIAN INSTITUTE. [VOL. XI 
Stokes’ original description of this species is as follows: ‘In this 
the tube is small; it is surrounded by numerous laminae or plates, 
filling up the siphuncle; but it is difficult to determine their nature. 
The external shell is slightly conical in form. From Lake Winnipeg, in 
yellowish-white limestone much resembling that from Igloolik.”’ 
Stokes’ figures show a siphuncle of about 28 mm. in diameter for a 
shell diameter of 53 mm. The nummuloidal rings are evenly rounded 
and fill the whole space between the septa, which are 8.5 mm. apart. 
The figures also show an irregularity in the development of the rings. 
Foord (op. cit.) gives the spacing of the septa as 8 mm. at a shell 
diameter of 75 mm. He emphasises the vertical calcareous lamellae 
and the strongly orad curvature of the septa. 
Whiteaves (op. cit.) states that the relative size of shell and siphuncle 
varies, though the maximum diameter of the latter is usually more than 
half that of the former. The posterior segment shown in his figures 
measures 36 mm. in breadth by 9 mm. in height and the anterior seg- 
ment is 47 mm. in width by 10 mm. in height: ten segments intervene 
between these two. 
The present specimen consists of a fragment 150 mm. long and 120 
mm. wide, showing parts of 16 septa and 17 nummuloidal siphuncular 
rings. The maximum diameter of the siphuncle is 55 mm. at a point 
where the shell is probably 120 mm. in diameter. While it is hazardous 
to state definitely the size of the shell in a broken specimen such as this, 
it would appear that the siphuncle is somewhat less than half the dia- 
meter of the shell. Whiteaves’ figures show the siphuncle to be within 
6 mm. of the shell at a siphuncle diameter of 49 mm. and a shell diameter 
of 83 mm. Our specimen shows a minimum distance of 15 mm. between 
the siphuncle and the shell at a siphuncle diameter of 55 mm. These 
figures are not contradictory if we consider that our fragment is more 
orad than that referred to by Whiteaves. The relation between the 
height and width of the siphuncular segments is somewhat variable, 
but averages about 8 to 53; in the type figure this ratio is 8.5 to 28, and 
in Whiteaves’ example it is 9 to 26 posteriorly and 10 to 47 anteriorly. 
It is apparent from Whiteaves’ figures that the segments are relatively 
wider orad. Between the type, Whiteaves’ example and our specimen, 
there is a discrepancy in these figures which may in part be explained 
by the different positions of the specimens relatively to the whole shell. 
Nevertheless, this difference is one reason for making a new variety of 
our specimen. 
The septa arch strongly forward, particularly on the siphonal side, 
and occur to the number of 16 in a distance of 130 mm. The siphuncular 
funnels are short and extend about 2 mm. apicad. The inner parts of 
