SUB-ORDER B TREPOSTOMATA 275 
bo 
Callopora, Hall (emend. Ulrich), (Fig. 456). Zoaria usually ramose and bushy, the 
branches often anastomosing. Apertures closed in the perfect state by perforated, 
often ornamented, covers, which are left behind, as growth proceeds, to form floors 
(diaphragms) of succeeding layers. Zocecial tubes of two sizes in the axial region, the 
larger ones with six to eight sides, the smaller set four- or five-sided. Ordovician and 
Silurian. 
Diplotrypa, Nich. emend. Ulrich (Dianulites, Zittel non Dybowski), (Fig. 457). 
Zoaria discoid, globular, or irregularly massive, generally free. Zocecial tubes com- 
paratively large, prismatic, with horizontal diaphragms. Mesopores few to numerous, 
varying in size. Ordovician. 
Monotrypa, Nich. (Dianulites, Dyb. p.p.; Ptychonema, Hall), (Fig. 458). — Dis- 
tinguished from the preceding by the absence of mesopores and fewer diaphragms. 
Ordovician to Devonian. 
Family 4. Trematoporidae. Ulrich. 
Zoaria ramose or encrusting.  Zoecial tubes irregular in the axial region, their 
proximal ends with diaphragms, and usually constricted where the latter occur; walls 

Fic. 459. 
Tangential sections of Batostoma from the Lower Trenton of Minnesota. 4A, B. fertile, Ulr., 4/4. B, Same, 
var. circulare, 14/;. C, B. Winchelli, var. spinulosum, Ulr., 38/; (after Ulrich). 
thickened in the mature region, lines of contact distinct. Mesopores generally abundant, 
usually of large size, their apertures 
closed. Acanthopores more or less 

thy 
abundant. Ordovician. ie. 
This family is principally distinguished — +es$4 
from the Calloporidae by the presence of 
acanthopores and closed mesopores. 
Batostoma, Ulrich (Fig. 459). 
Branches irregular, springing from a 
large basal expansion. Zocecial walls 
of varying thickness, in contact only 
at limited points, and of two sizes in 

iy 
@ores 

the axial region, Diaphragms strong, Ed. 
hori is ke Hemiphragma irrasum, Ulr. Lower Trenton ; Minnesota. 
orizontal, complete. Species numer A, Vertical section, 7/;. B, Tangential, 14/, (after Ulrich). 
ous and mostly very abundant. 
Hemiphragma, Ulrich (Fig. 460). Like Batostoma, but diaphragms in peripheral 
part of tubes incomplete. 
Trematopora, Hall (emend. Ulrich) ; Stromatotrypa, Ulrich. 
