72 
Remarks. From Cleiothyridina incrassata of the Burlington of Mis- 
sissippi valley this species differs especially in its more transverse form. 
From C . obmaxima of the Upper Kinderhook, Burlington, and Keokuk 
of the same region it differs in its smaller sinus and fold, narrower spines, 
and in having the greatest convexity of the brachial valve in the posterior 
and not anterior part. 
Locality and Horizon . In the Minnewanka region in the Mississippian 
of sections 2-23 (c), 25 (c); 35 (R); 4-3 (R). 
Cleiothyridina hirsuta (Hall) 
1857. Spirifera hirsuta Hall, Trans. Albany Inst., vol. 4, p. 8; Athyris 
hirsuta Whitfield, 1882, Bull. Am. Mus. Nat. Hist., vol. 1, p. 49, 
PI. 6, figs. 18-21; Hall, 1883, 12th Ann. Rept. Geol. Surv., Indiana, 
p. 328, PI. 29, figs. 18-21; Walcott, 1884, Pal. Eureka District, p. 222, 
PI. 18, fig. 5; Cliothyris roysii Hall and Clarke, 1895, Pal. N. Y., 
vol. 8, pt. 2, PI. 46, fig. 23 (not fig. 24) ; C. hirsuta Hall and Clarke, 
1895, Pal. N.Y., vol. 8, pt. 2, PI. 46, figs. 25-28; Cleiothyris hirsuta 
Beede, 1906, 30th Ann. Rept. Geol. Surv., Indiana, p. 1320, PI. 19, 
figs. 1-la, PI. 22, figs. 18-21; Cleiothyridina hirsuta Weller, 1914, 
Geol. Surv., Illinois, Mon. 1, p. 479, PI. 80, figs. 13-24. 
Remarks . Our single, somewhat crushed specimen agrees closely 
with C. hirsuta. The rather strong concentric growth ridges argue that 
it is an adult shell; otherwise it somewhat resembles the young of C. 
parvirostris. This species is very similar to C. crassicardinalis var. nana 
Girty from the Madison limestone of Yellowstone National park. 1 Girty 
informs me that the brachial valves associated with the type pedicle valve 
(none of the specimens retain both valves in conjunction) are subequal 
in convexity with the pedicle valves, “the dorsal valve being somewhat, 
though distinctly, more inflated than the ventral.” This is similarly 
true of the Mississippi Valley C. hirsuta. Girty’ s C. nana appears to 
differ mainly in the greater angle made at the beak of the pedicle valve 
by the lateral umbonal slopes. The type figure gives 135 degrees, whereas 
C . hirsuta measured from Weller’s figures 2 gives nowhere greater than 
115 degrees, and for specimens the size of C. nana the angle is about 108 
degrees. In this respect our specimen agrees with C. hirsuta , having an 
angle of about 110 degrees. C. crassicardinalis (White) has the pedicle 
valve much more convex than the brachial. 
Locality and Horizon. Middle Mississippian of Mississippi valley. 
In the Minnewanka region in the Lower Mississippian of section 2-22 (R) . 
Genus, Composita Brown 
Composita humilis (Girty) 
1899. Seminula humilis Girty, U.S.G.S., Mon. 32, pt. 2, p. 565, PI. 71, 
figs. 6 a-c. 
Remarks. Certainty of identity is, of course, impossible where 
external form alone is available for comparison, but within these limits 
the Minnewanka specimens fall within Girty’s species. 
Locality and Horizon. Mississippian of Yellowstone National park. 
In the Minnewanka region in the Mississippian of section 2-24 (C). 
1 U.S. Geol. Surv., Mon. 32, pt. 2, p, 569, PI. 71, fig. 9a. 
* Loc.cit. 
