Revision of Bryosoan Genera.—Cumings. 199 
tubes pass from the axial into the peripheral region, are more than only 
very slightly thickened. Spiniform tubuli in the typical species few, 
but very large, and not infrequently already present in the axial region 
of the zoarium. In other species (D. appressa n. sp. and D. paupera 
n. sp.) they are reduced in size but their number remains about the 
same. In one (D. multispinosa n. sp.) they are also comparatively small, 
but more numerous. When in good state of preservation, at certain 
stages in the growth of the zoarium, the cell-apertures over larger or 
smaller patches of the surface are covered by a thin calcareous pellicle, 
On such covered spots the spiniform tubuli are very conspicuous. Dia- 
phragms straight, usually few, sometimes almost entirely absent, oc- 
casionally (in the peripheral region) from one-half to one tube-di- 
‘ameter distant from each other.” * 
In Zittel’s Paleontology (Eastman’s translation) we have 
Dekayia “distinguished from Dekayella by the absence of the 
smaller set of acanthopores, and lesser number of mesopores 
and diaphragms” (p. 273). 
Under this genus as thus defined are now placed five species 
from the Cincinnati group, and one, doubtfully, from the 
Hamilton group.* 
Heterotrypa.—This name was proposed in 1879 by Nichol- 
son ¥ for a subgenus of the genus Monticulipora D’Orb., with 
the following definition : 
“Heterotrypa, Nich—Corallites of two or sometimes of three 
kinds; the larger ones subpolygonal partially separated by the de- 
velopment of numerous smaller circular or irregularly shaped tubes 
[mesopores], of which there is no more than a single row. Walls 
thickened towards the mouths of the tubes. Tabule [diaphragms] 
conspicuously more numerous in the smaller tubes than in the larger 
ones. Type of the group the Monticulipora mammulata D’Orb. [— 
Heterotrypa frondosa of Ulrich and others] (which is also the type 
of the whole genus.’’) 
Under the subgenus as thus defined, Nicholson places 
(Ibid., p. 293) besides Monticulipora mammulata, M. ramosa 
Edwards and Haime. M. rugosa E. & H., M. frondvsa D’Or- 
bigny, (=Peronopora dicipiens Rominger sp.) M. Jamesi 
Nich., M. moniliformis Nich., M. tumida Phillips, M, gracilis 
James, “and various other more or less certainly established 
species.” In his monograph on the genus Monticulipora 
(1881) M. frondosa is removed to the subgenus Peronopora,? 
and the complete list of species placed under the subgenus 
tin ap) pi 
* Bull. U. S. G. S. No. 173. 1900, pp. 228, 229. 
+ Paleozoic Tabulate Corals, p. 291. 
t Op. Cit.. p. 215. 
