62 The American Geologist. July, 1892 
material, wherefore the more delicate structural details are some- 
what obscured. Still, in thin sections, the principal features of 
the species are sufficiently plain for recognition. Width of the 
tubes, one-third of a millimeter; shape of the orifices quite irreg- 
ular, somewhat rounded and longer in one direction than in 
the other, with conspicuous indentations of the cavities b}' two, 
three, or four of the larger vertical crests. The intermediate 
smaller columelles, though plainly recognizable in cross sec- 
tions, do not cause indentations of the margins. In longitud- 
inal sections, the striated surface of the walls, the intersection of 
the tubules by moderately numerous transverse diaphragms, the 
.concentric superposition of new la3'ers without an interruption in 
the continuity of the tubules, and the multiplication by lateral or 
marginal gemma?, are all features readily observable. 
The material at my disposal is not sufficient to determine 
whether the second form, which I obtained from Prof. Schliiter 
in Bonn, is really a diffei'ent species. It grows in thick, flat ex- 
pansions, which have been described and figured by Prof. 
Schliiter under the name Calainopova pUiformis. I refer to his 
own figures and explicit descriptions, from which the identity of 
his species with Chnfetes becomes evident before one subjects 
the fossil itself to a scrutinous examination. 
The margins of the irregularly polygonal, somewhat rounded 
•orifices are indented by two or three, but not rarely by four and 
five, crest-like projections, and the intermediate portion of the 
margins shows the outlines of smaller columelles taking part in 
the formation of the walls. The tubules, one-third of a milli- 
meter wide, ascend almost parallel with each other from the base 
of the expansions to their upper surface without an obvious inter- 
ruption except by numerous transverse diaphragms, distant a little 
more thtvn one tube diameter. Not a trace of lateral connecting 
pores can be discovered, and as Prof. Schliiter is fully aware of 
that fact, I feel somewhat surprised, that he unreservedly places 
this form under the genus Calamopora, a synonym of Favosites. 
EXPLANATION OP PLATE. 
Fig3. IS, MONOTRYPA TENNIS Hall, Sp. 
1. Small portion of tangential section, X 35, showing structure of 
'walls and one of the acanthopores. 
2, Portion of vertical section, X 18, showing an acanthopore, the 
ibeaded structure of some of the walls, and several diaphragms. 
