29 
Litkostrotion sp. 
Description. Corallum compound, massive. Corallites crowded, 
polygonal in cross-section, of very uniform diameter, about 4 mm. Calyx 
comparatively deep, its bottom occupied by a broad convexity (half the 
width of the corallite) rising to the central, low, compressed columella. 
Septa apparently 20 to 25 in number, extending half-way or more toward 
the centre; there are some indications of short, alternating, secondary septa 
Remarks . This form is too poorly preserved to admit of a good des- 
cription. In our field notes we called it L. mamillare parvum as it looks 
much like a very small L. mamillare. All our specimens are completely and 
grossly silicified. When broken from the rock they are almost structureless, 
but when weathered out they present the characters noted above. 
Locality and Horizon . In the Minnewanka region in the Pennsylvanian 
of sections 1-34 (C); 2-8 (C); 3a-4 (c). 
Genus, Aulopora Goldfuss 
Avlopora geometrica Girty 
1899. Avlopora geometrica Girty, U.S. Geol. Surv., Mono. 33, pt. 2, p. 508, 
PI. 67, fig. 6a. 
Remarks . Our few specimens exhibit all the characters noted in this 
species. 
Locality and Horizon. In the Lower Mississippian of the Yellowstone 
National park. In the Minnewanka region in the Lower Mississippian 
of section 2-30 (r). 
Avlopora curva n. sp. 
Plate Y, figures 6, 7, 8 
Description . Corallum spreading over mud of sea bottom, probably 
attached only by earliest corallites, forming a broad colony several feet in 
diameter. 
Corallites budding from the side or base of the parent at an angle 
usually of 40 degrees. Seldom do two corallites grow from a single individ- 
ual. The young, budding off at about the middle of the parent corallite, 
expand gradually to a diameter of about 3 mm. and to a height of from 
3 mm. to 6 mm. above the plane of budding. Usual length of corallite 
10 mm. to 15 mm., curved gently upward throughout its entire length 
(whence the specific name). The young is partly separated from the 
parent by a thickening of the walls, but remains united by a persistent 
pore. 
Locality and Horizon . In the Minnewanka region in the Pennsylvanian 
of sections 1-24 (C); 2-8 (C); 3a-l (c). 
10277—3 
