200 The American Geologist. April, 1902. 
Heterotrypa is: Monticulipora mammulata D’Orb., M. tumida 
Phill. M. ulrichi Nich., M. gracilis James, M. andrewsii Nich., 
M. ramosa D’Orb., M. rugosa E. & H., M. dalei E. & FL, M. 
moniliformis Nich., M subpulchella Nich., M. onealli James, 
M. nodulosa Nich., M. jamesi Nich., M. implicata Ulrich, M. 
girvanensis Nich., M. trentonensis Nich., and M. dawsoni Nich., 
In 1883 Mr. E. O. Ulrich, in hts American Paleozoic Bryo- 
zoa,* again revised the group, limiting Heterotrypa (by him 
ranked as a genus) to two of the above species, H. frondosa 
(=Monticulipora (Heterotrypa) mammulata Nich.) and H. 
subpulchella, and himself adding several new species. The re- 
mainder he distributes among the genera Callopora Hall, Am- 
plexopora Ulrich, Homotrypa Ulr., Batostoma Ulr., Batostom- 
ella Ulr., and Monotrypella Ulr. 
Mr. Ulrich’s definition of the genus as thus restricted is: 
“Zoarium growing from an expanded base, attached to foreign 
objects, upward into simple, often undulated or irregularly inoscu- 
lated fronds, and occasionally into flattened branches. Cell-apertures 
varying in shape from polygonal to circular. They are separated from 
each other by walls or interspaces, which may be comparatively thin 
(H. solitaria), or nearly as thick as their own diameter ( H. vaupeli). 
Interstitial cells from few to very numerous, always angular or sub- 
angular. Spiniform tubuli [acanthopores] small, usually numerous 
(sometimes excessively so, as in H. vaupeli) occasionally inflecting the 
walls, and giving the cell apertures an irregular petaloid appearance. 
Internally we find that the walls of the tubes are more or less thick- 
ened as they enter the ‘mature’ region and apparently amalgamated with 
one another. The diaphragms are straight, of one kind only, more 
numerous in the interstitial tubes than in the proper zocecia, and 
always more crowded in the ‘mature’ regions than in the ‘immature’ 
or axial region.” t 
The genus as thus defined includes, according to Nickles 
and Basslert nine species from the Cincinnati group of the 
Ohio valley and Illinois, and two species from the Hamilton, 
doubtfully placed in this genus. 
Dekayella Ulrich.—This genus was founded in 1882 by Mr. 
Ulrich. The following is his original diagnosis: § 
“Dekayella, Ulrich—Ramose, branches often compressed. Inter- 
stitial cells more or less numerous, often aggregated into irregular. 
* Jour. Cin. Soc. Nat. Naat vol. vi, p. 83. A brief diagnosis is given on 
% Mibu woie vi pS ‘86. 
t Ball, U.S. G. 5. No. 173, 1900, pp. aaa 290. 
§ Jour. Cin, “Soc. Nat. Hist., vol. v, p. 15 
