64 
Genus, Pseudosyrinx Weller 
Pseudosyrinx gigas Weller 
1914. Pseudosyrinx gigas Weller, State Geol. Surv., 111., Mon. 1, p. 410, 
PI. 66, figs. 1-5. 
Remarks. Some specimens from the Minnewanka region apparently 
belong to this species, though certain differences are observable. A rather 
poorly preserved pedicle valve from section 2-23 has a length of 35+ mm., 
width along the hinge-line of 64 mm., height of cardinal area of 24 mm., 
width of delthyrium at base 14 mm., angle formed by the lateral margins 
of the cardinal area, about 100 degrees; (Weller’s type specimen gives 
similarly 50 mm., 82 mm., 43 mm., 18 mm., and about 100 degrees); hinge- 
line longer than width of shell below; cardinal extremities angular. Car- 
dinal area fiat, its lateral margins rounding rather abruptly into the lateral 
slopes of the valve; its base makes apparently an angle of about 90 degrees 
with the junction of the valves; the fiat delthyrial plate is sunk but little 
below the level of the cardinal area near the apex, but at its termination 
in the middle of the area it is over a millimetre below this level; pseudo- 
deltidium not preserved; strong deltidial plates are present, diverging at 
the same angle as the median sinus. Surface with concentric growth lines 
becoming conspicuous anteriorly; there are faint indications of 6 or 8 very 
low, broad plications upGn each lateral slope of the valve, but these dis- 
appear towards the cardinal extremities and they are similarly absent from 
the median sinus. Entire surface covered with minute, low, elongate 
papillae, giving a striate appearance to the shell. This specimen is inter- 
mediate in size between P. missouriensis and P. gigas , but approaches more 
nearly to the latter in the abrupt rounding of the lateral margins of the 
cardinal area, the angular cardinal extremities, and the poorly-defined 
plications. A brachial valve 28 mm. long by 50 mm. wide has 12 to 14 
low, broad plications upon each lateral slope; these plications are much 
stronger than those of the preceding pedicle valve and extend to the front 
of the shell; this is shown also in a specimen retaining both valves. 
The Minnewanka specimens appear to differ from the typical P. 
gigas merely in their smaller size. These specimens differ from Syringo - 
thyris in the absence of the syrinx and from Spiriferella in their more 
elevated and less arched cardinal area as well as in their longer hinge-line 
and more angular cardinal extremities. 
Locality and Horizon . Mississippian (Keokuk) of Mississippi valley. 
In the Minnewanka region in the Mississippian of section 2-22 (?), 23 (r), 
24 (R), 26 (?), 29 (C), 30 (r), 34 (r). 
Genus, Spiriferella Chemuishev 
Spiriferella minnewankensis n. sp. 
Plate III, figures 1 a, b, c, d; 2 a, b, c 
Description. Shell slightly above medium size, usually wider than 
long, with greatest convexity posterior to the middle. Hinge-line shorter 
than greatest width; cardinal extremities rounded. The dimensions of 
a rather large shell from the higher beds are: greatest length 30 mm., 
greatest width (about 8 mm. anterior to the cardinal area) 33 mm.; length 
of hinge-line about 18 mm.; thickness 25 mm.; greatest convexity of 
pedicle valve (at umbo) 15 mm., of brachial valve (at middle of valve) 
10 mm.; delthyrium 11 mm. wide at base and about 11 mm. high. 
