OF DENISON UNIVERSITY. 
173 
terstitial cells, more or less numerous, sometimes completely isolating 
the proper zosecia. Diaphragms numerous. Spiniform tubuli and 
cystoid diaphragms wanting.” (Ulrich, Am. Pal. Bry. ) The follow- 
ing species are provisionally referred here on account of an apparently 
similar relation between cells and interstitial cells. 
XX. Callopora magnopora, sp. n. 
{Plate XVI, Fig. 5 ; Plate XVII, Fig. 16.) 
Zoaria branching at intervals of about 15 mm; branches from 6.5 
to 8 mm. in diameter, rather irregular in form and often with low tu- 
bercles of no marked characteristics, and which may be entirely ab- 
sent. Cells about 8 in a distance of 3 mm. Cell apertures sub-circu- 
lar, the margins not distinguishable at the point of contact, but distinct 
and elevated along the rest of the cells, apparently enclosing intersti- 
tial cells, these appearances obscured by abrasion. Tangential sec- 
tions seem to give better evidence of interstitial cells, these being 
smaller, irregular, rather fewer m number, and more or less surround- 
ing the more circular cells. In longitudinal sections the interstitial 
cells may apparently be also detected, being narrower cells with some- 
what more numerous diaphragms. In one specimen there were 10 
diaphragms in a length of i mm. in the cells, in the interstitial cells 
13 or 14 were found. 
This species is readily distinguished from the last by the larger 
size of the cell apertures, being about one and a half times the size of 
that species. When the number of the cells is approximately the same 
this may be accounted for by the fact that, whereas in the former spe- 
cies there is a considerable space left between the margins of the cells, in 
this species they are united into one cell wall, indistinguishable at the sur- 
face. The number of diaphragms is also much greater in this species. 
However, if the presence of interstitial cells has been correctly deter- 
mined, this offers no ready character for determination, since abraded 
specimens and even moderately well preserved specimens are scarcely 
distinguishable by superficial examination in appearance from the last 
species. The name signifies large pored or celled. 
Locality and position. Centreville, Soldiers’ Home Quarry, Clin- 
ton Group. 
