-_>ss 
The American Geologist. 
May, 1891 
MISCELLANEOUS. 
NEAREST RELATIVES. 
25. 
Dybowski did not determine the nature of the outei 'ip ycn0 phyii uin 
zone. Provisionally placed in this division. 
26. 
The columella is formed hy manifold, irregular twist ]g tl . epte j asma 
ing and anastomosing of the primary septa. 
27. 
Bottom of calyx may be smooth, have a conical tu- 
bercle, a small ridge or a variously formed columel- Zaphrentis. 
lar projection. 
28. 
Columella is generally in continuity with small sep- 
tum in fovea and sometimes with opposite, pri- 
mary septum. 
Cyathaxonia. 
29. 
Principal septum in principal fovea, towards which] 
is turned the concavity of the crescentiform tab- Amplexus. 
ulae. 
30. 
Septa are arranged in four groups but no cross is 
formed. 
Zaphrentis. 
31. 
Loosely aggregated in its growth. 
Streptelasma. 
32. 
The two septa bounding the fovea and the three prin- 
cipal septa strongly developed. Sometimes but four 
strongly developed septa occur. 
1. Phryganophyllum. 
2. Polycoalia. 
33. 
Four large principal septa form a right-angled cross. 
Polycoelia. 
34. 
One septum of each pair stronger than the other. 
Zaphrentis. 
35. 
The septa are formed by a sharp infolding of the con- 
" tinuous cell cups. Type has radiciform processes. 
Omphyma. 
36. 
Densiphyllum. 
37. 
Not more than two or three ascending stems pro- 
duced. 
Amplexus. 
38. 
The fine tubes forming the columella are branched 
and anastomosed. 
1. Streptelasma. 
2. Grewingkia. 
39. 
The spongy core seems to be formed by contortions 
of the septa and the introduction of additional 
structure. 
1. Palseophyllum. 
2. Grewingkia. 
40. 
Tabulae are frequently deflected downwards near the 
wall. Fovea is formed by a coalescence of septa. 
1. Amplexus. 
2. Cyathophylloides. 
41-. 
Heliophyllum. 
42. 
A secondary wall is indicated about the pit by a 
thickening of the septa. A true wall seldom occurs. 
1. Endophyllum. 
2. Cyathophyllum. 
43. 
Central eminence is formed entirely by the elevated 
and twisted tabulae and not by the septa. 
Kon i nckoph yllum . 
44. 
The vertical plates of the central area are quite inde- 
pendent of the septa. Median one is stronger and 
in fovea. 
1. Dibunophyllum. 
2. Clisiophylhun. 
45. 
The pinnate septa may, alternately, intercross at the 
bottom of the fovea. Flexuous and irregular. 
" Hallia. 
46. 
The inner Mall divides the visceral chamber into a 
central, columnar and an outer, annular area. 
Cyclophylhim. 
47. 
Columella is formed of numerous, vertical, spirally 
twisted lamella?. 
Lonsdaleia. 
48. 
Distinctly made up of a series of invaginated cell 
cups with projecting edges. Wall is frequently 
absent. 
Cyathophyllum. 
* From an examination of A. mitratum, Dr. Lindstrom considers the genus of 
•doubtful value. Mr. <;. K. Greene has in his possession over a hundred specimens 
the type, A. sulcatum, from the Falls of the Ohio, which he writes proves the 
